Editing Leaning Tower of Pisa

{{short description|Bell tower in Pisa, Italy}}
{{Redirect|The Leaning Tower|the Finnish film|The Leaning Tower (film)}}
{{pp-semi-indef}}{{pp-move-indef}}
{{Use dmy dates|date=August 2020}}
{{Infobox religious building
| building_name        = Leaning Tower of Pisa
| native_name          = Torre pendente di Pisa
| native_name_lang     = it
| image                = Italy - Pisa - Leaning Tower.jpg
| caption              = Leaning Tower of Pisa in 2022
| location             = [[Pisa]], [[Italy]]
| coordinates          = {{coord|43|43|23|N|10|23|47|E|type:landmark_region:IT-PI|display=inline,title}}
| religious_affiliation= [[Catholic Church]]
| province=
| district=
| status               = Active
| functional_status=
| heritage_designation= 
| website              = {{URL|www.opapisa.it}}
| architecture         = yes
| architect            = [[Diotisalvi]] (?)<br />[[Bonanno Pisano]] (?)
| architecture_type=
| architecture_style   = [[Romanesque architecture|Romanesque]]
| groundbreaking       = 1173
| year_completed       = {{start date and age|1372}}
| height_max           = {{cvt|55.86|m|ftin|frac=2}}
| materials            = {{Flatlist|
* [[marble]]
* [[Rock (geology)|other stone]]
}}
| footnotes            = {{Infobox UNESCO World Heritage Site
  |child = yes
  |Part_of = [[Piazza dei Miracoli|Piazza del Duomo]], Pisa
  |ID = 395
  |Year = 1987
  |Criteria = Cultural: i, ii, iv, vi
  }}
}}

The '''Leaning Tower of Pisa''' ({{langx|it|torre pendente di Pisa}} {{IPA|it|ˈtorre penˈdɛnte di ˈpiːza, - ˈpiːsa|}}<ref>{{cite web|url=http://www.dipionline.it/dizionario/ricerca?lemma=Pisa|title=DiPI Online|language=it|work=Dizionario di Pronuncia Italiana|access-date=26 December 2020|archive-date=30 October 2020|archive-url=https://web.archive.org/web/20201030075750/http://www.dipionline.it/dizionario/ricerca?lemma=Pisa|url-status=live}}</ref>), or simply the '''Tower of Pisa''' ({{lang|it|torre di Pisa}}), is the {{lang|it|[[bell tower|campanile]]}}, or freestanding bell tower, of [[Pisa Cathedral]]. It is known for its nearly four-degree lean, the result of an unstable [[Foundation (engineering)|foundation]]. The tower is one of three structures in [[Pisa]]'s Cathedral Square ({{lang|it|[[Piazza dei Miracoli|Piazza del Duomo]]}}), which includes the cathedral and [[Pisa Baptistery|Pisa Baptistry]]. Over time, the tower has become one of the most visited tourist attractions in the world as well as an architectural icon of [[Italy]], receiving over 5 million visitors each year.<ref>{{Cite web |last=Bronzini |first=Andrea |title=Tower Facts |url=https://leaningtowerpisa.com/facts |access-date=2025-01-12 |website=Leaning Tower Pisa |language=en-gb}}</ref>

The height of the tower is {{convert|55.86|m|ftin|frac=2|abbr=off}} from the ground on the low side and {{convert|56.67|m|ftin|frac=2|abbr=on}} on the high side. The width of the walls at the base is {{convert|2.44|m|ftin|frac=2|abbr=on}}. Its weight is estimated at {{convert|14500|t|ST||abbr=off}}.<ref>{{cite web|url=http://www.towerofpisa.info/Tower-of-Pisa-facts.html|title=Leaning Tower of Pisa Facts|publisher=Leaning Tower of Pisa|access-date=5 October 2013|archive-date=11 September 2013|archive-url=https://web.archive.org/web/20130911021639/http://www.towerofpisa.info/Tower-of-Pisa-facts.html|url-status=live}}</ref> The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase.

The tower began to lean during construction in the 12th century, due to soft ground which could not properly support the structure's weight. It worsened through the completion of construction in the 14th century. By 1990, the tilt had reached 5.5 degrees.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/europe/793432.stm|title=Europe &#124; Saving the Leaning Tower|date=15 December 2001|work=BBC News|access-date=9 May 2009|archive-date=21 September 2013|archive-url=https://web.archive.org/web/20130921054206/http://news.bbc.co.uk/2/hi/europe/793432.stm|url-status=live}}</ref><ref>{{cite web|url=http://www.archidose.org/Jul00/071000.html|title=Tower of Pisa|date=17 June 2001|publisher=Archidose.org|archive-url=https://web.archive.org/web/20090626231030/http://www.archidose.org/Jul00/071000.html|archive-date=26 June 2009|url-status=usurped|access-date=9 May 2009}}</ref><ref>{{cite encyclopedia|url=https://www.britannica.com/EBchecked/topic/333926/Leaning-Tower-of-Pisa|title=Leaning Tower of Pisa (tower, Pisa, Italy) |encyclopedia=Britannica Online Encyclopedia |access-date=9 May 2009|archive-date=8 March 2013|archive-url=https://web.archive.org/web/20130308040547/https://www.britannica.com/EBchecked/topic/333926/Leaning-Tower-of-Pisa|url-status=live}}</ref> The structure was stabilized by remedial work between 1993 and 2001, which reduced the tilt to 3.97 degrees.<ref>{{cite news |title=Leaning tower of Pisa loses crooked crown |url=https://www.irishtimes.com/news/leaning-tower-of-pisa-loses-crooked-crown-1.980085 |access-date=10 June 2020 |work=Irish News |archive-date=28 November 2020 |archive-url=https://web.archive.org/web/20201128203805/https://www.irishtimes.com/news/leaning-tower-of-pisa-loses-crooked-crown-1.980085 |url-status=live }}</ref>

== Architect ==
The identity of the architect of the tower is a subject of controversy. The design had long been attributed to a man named Guglielmo and to [[Bonanno Pisano]], the latter a well-known 12th-century resident artist of Pisa known for his [[bronze casting]], particularly in the [[Piazza dei Miracoli|Pisa Duomo]].<ref>{{Cite web|url=http://www.endex.com/gf/buildings/ltpisa/ltpinfo/pisano.htm|archive-url=https://web.archive.org/web/20070813230458/http://endex.com/gf/buildings/ltpisa/ltpinfo/pisano.htm|title=Endex.com|archive-date=13 August 2007|website=endex.com}}</ref>{{Better source needed|date=April 2022|reason=A scholarly source to verify this information would be helpful.}} Pisano left Pisa in 1185 for [[Monreale]], Sicily, only to return and die in his home town. A piece of cast bearing his name was discovered at the foot of the tower in 1820, but this may be related to the bronze door in the façade of the cathedral that was destroyed in 1595. A 2001 study seems to indicate [[Diotisalvi]] was the original architect, due to the time of construction and affinity with other Diotisalvi works, notably the bell tower of [[San Nicola, Pisa|San Nicola]] and the [[Baptistery]], both in Pisa.<ref>Pierotti, Piero. (2001). ''Deotisalvi – L'architetto pisano del secolo d'oro.'' Pisa: Pacini Editore</ref>{{page needed|date=August 2020}}

<gallery>
File:Leaning tower of Pisa - capital of column at the top.jpg|Column capital details on top level
File:Torre di pisa, capitello con scimmiette.JPG|Column details
File:Pisa. Torre 02.JPG| Base wall columns
File:Pisa, torre pendente (18).jpg|Flower pendant
File:Pisa. Torre 01.JPG|Entrance
File:Animals and monsters on the wall of the leaning tower of Pisa.jpg|Wall relief details of animals
File:Torre di Pisa - panoramio (18).jpg|Outer floor tiles
File:Leaning tower bell assunta.JPG|''Assunta'' bell
File:Pisa Leaning Tower bell San Ranieri.jpg|''Pasquareccia'' bell
File:Cos de campanes de la torre de Pisa.JPG|Top-level bells
</gallery>

== Construction ==
Construction of the tower occurred in three stages over 199 years. On 5 January 1172, Donna Berta di Bernardo, a widow and resident of the house of dell'Opera di Santa Maria, bequeathed sixty [[Soldo|soldi]] to the {{Lang|la|Opera Campanilis petrarum Sancte Marie}}. The sum was then used toward the purchase of a few stones which still form the base of the bell tower.<ref>Capitular Record Offices of Pisa, parchment n. 248</ref> On 9 August 1173, the foundations of the tower were laid.<ref name=":1">{{Cite book |url=https://books.google.com/books?id=37PStsDpevoC&pg=PA254 |title=Finite Element Analysis in Geotechnical Engineering: Application |last1=Potts |first1=David M. |last2=Zdravković |first2=Lidija|author2-link=Lidija Zdravković |date=2001 |publisher=Thomas Telford |isbn=9780727727831 |pages=254 |language=en |access-date=5 August 2019 |archive-date=18 September 2019 |archive-url=https://web.archive.org/web/20190918235637/https://books.google.com/books?id=37PStsDpevoC&pg=PA254 |url-status=live }}</ref> Work on the ground floor of the white marble campanile began on 14 August of the same year during a period of military success and prosperity. This ground floor is a [[blind arcade]] articulated by engaged columns with classical [[Corinthian capitals]].<ref name=Toy1920>{{cite journal |journal=Indian Engineerion | url=https://books.google.com/books?id=cd27sERYahEC&pg=PA302 |title=The Campanile of Pisa |last=Toy |first=Sidney| volume=68 |year=1920|via=Google Books}}</ref> Nearly four centuries later [[Giorgio Vasari]] wrote: "Guglielmo, according to what is being said, in the year 1174, together with sculptor Bonanno, laid the foundations of the bell tower of the cathedral in Pisa".<ref>{{Cite book |url=https://archive.org/details/leoperedigiorgio08vasa |title=Le opere di Giorgio Vasari: Le vite de' più eccellenti pittori, scultori ed architettori |last=Vasari |first=Giorgio |date=1878 |publisher=[[Sansoni (publisher)|G.C. Sansoni]] |pages=[https://archive.org/details/leoperedigiorgio08vasa/page/274 274] |language=it |oclc=15220635 |quote=Guglielmo, secondo che si dice, l'anno 1174, insieme con Bonanno scultore, fondò in Pisa il campanile del Duomo, dove sono alcune parole}}</ref>

The tower began to sink after construction had progressed to the second floor in 1178. This was due to a mere three-metre foundation, set in weak, unstable [[subsoil]], a design that was flawed from the beginning. Construction was subsequently halted for the better part of a century, as the [[Republic of Pisa]] was almost continually engaged in battles with [[Republic of Genoa|Genoa]], [[Republic of Lucca|Lucca]], and [[Florence]]. This allowed time for the underlying soil to settle. Otherwise, the tower would almost certainly have toppled.<ref name="pbs-nova">{{cite web |title=Fall of the Leaning Tower – History of Interventions |url=https://www.pbs.org/wgbh/nova/pisa/interventions.html |website=NOVA Online (PBS) |access-date=24 April 2019 |year=1999 |archive-date=24 April 2019 |archive-url=https://web.archive.org/web/20190424081312/https://www.pbs.org/wgbh/nova/pisa/interventions.html |url-status=live }}</ref> On 27 December 1233, the worker Benenato, son of Gerardo Bottici, oversaw the continuation of the tower's construction.<ref>Public Record Offices of Pisa, Opera della Primaziale, 27 December 1234</ref>

On 23 February 1260, Guido Speziale, son of [[Giovanni Pisano]], was elected to oversee the building of the tower.<ref>Public Record Offices of Pisa, Opera della Primaziale, 23 February 1260</ref> On 12 April 1264, the master builder [[Giovanni di Simone]], architect of the [[Camposanto Monumentale di Pisa|Camposanto]], and 23 workers went to the mountains close to Pisa to cut the required marble. The cut stones were given to Rainaldo Speziale, worker of St. Francesco.<ref>Public Record Offices of Pisa, Roncioni, 12 April 1265.</ref> In 1272, construction resumed under Di Simone. In an effort to compensate for the tilt, the engineers built upper floors with one side taller than the other. Because of this, the tower is curved.<ref name="mclain">{{cite book |last=McLain |first=Bill |title=Do Fish Drink Water? |year=1999 |isbn=0688165125 |publisher=William Morrow and Company, Inc |location=New York |pages=[https://archive.org/details/dofishdrinkwater00mcla_0/page/291 291–292] |url-access=registration |url=https://archive.org/details/dofishdrinkwater00mcla_0/page/291 }}</ref> Construction was halted again in 1284 when the Pisans were defeated by the Genoese in the [[Battle of Meloria (1284)|Battle of Meloria]].<ref name=":1" /><ref>{{Cite book |url=https://books.google.com/books?id=gu9Ev_4PL5oC&pg=PA64 |title=Authentic Tuscany |last=Touring club italiano |date=2005 |publisher=Touring Editore |isbn=9788836532971 |pages=64 |language=en |access-date=5 August 2019 |archive-date=9 August 2021 |archive-url=https://web.archive.org/web/20210809133811/https://books.google.com/books?id=gu9Ev_4PL5oC&pg=PA64 |url-status=live }}</ref>

The seventh floor was completed in 1319.<ref>{{Cite book |url=https://books.google.com/books?id=q_5QDwAAQBAJ&pg=PT98 |title=Understanding Architecture: Its Elements, History, and Meaning |last=Roth |first=Leland M. |date= 2018 |publisher=Routledge |isbn=9780429975219 |pages=98 |language=en |access-date=5 August 2019 |archive-date=9 August 2021 |archive-url=https://web.archive.org/web/20210809133710/https://books.google.com/books?id=q_5QDwAAQBAJ&pg=PT98 |url-status=live }}</ref> The bell-chamber was finally added in 1372. It was built by [[Tommaso di Andrea Pisano]], who succeeded in harmonizing the [[gothic architecture|Gothic]] elements of the [[Belfry (architecture)|belfry]] with the [[Romanesque architecture|Romanesque]] style of the tower.<ref>{{Citation |author=G. Barsali |title=Pisa. History and masterpieces |publisher=Bonechi |year=1999 |page=18 |url=https://books.google.com/books?id=nZTRaipHNP8C&q=%22with+delicate+skill+managed+to+blend+in+the+Gothic+elements |isbn=8872041880 |access-date=25 August 2015 |archive-date=9 August 2021 |archive-url=https://web.archive.org/web/20210809133903/https://books.google.com/books?id=nZTRaipHNP8C&q=%22with+delicate+skill+managed+to+blend+in+the+Gothic+elements |url-status=live }}</ref><ref>{{Citation |author=Giorgio Vasari, Jean Paul Richter |title=Lives of the Most Eminent Painters, Sculptors, and Architects |publisher=H. G. Bohn |year=1855 |page=153 |url=https://books.google.com/books?id=GaYCAAAAYAAJ&q=Giorgio+Vasari+Tommaso+di+Andrea+Pisano&pg=PA153 |access-date=14 November 2020 |archive-date=9 August 2021 |archive-url=https://web.archive.org/web/20210809133918/https://books.google.com/books?id=GaYCAAAAYAAJ&q=Giorgio+Vasari+Tommaso+di+Andrea+Pisano&pg=PA153 |url-status=live }}</ref> There are seven bells, one for each note of the musical [[major scale]]. The largest one was installed in 1655.<ref name="pbs-nova" />
<!-- * One possible known builder of Pisa Tower was [[Gerardo di Gerardo]]. His name appears as a witness to the above legacy of Berta di Bernardo as "Master Gerardo", and as a worker whose name was Gerardo.
* A more probable builder was Diotisalvi, because of the construction period and the structure's affinities with other buildings in Pisa, but he usually signed his works, and there is no signature by him in the bell tower.
* Giovanni di Simone was known to be heavily involved in the completion of the tower, under the direction of Giovanni Pisano, who at the time was the master builder of the [[Opera di Santa Maria Maggiore]]. -->
[[File:Italy - Pisa - Cathedral Square.jpg|center|thumb|800px|Panoramic view (from left to right) of the [[Campanile]] (Leaning Tower of Pisa), the [[Pisa Cathedral]], and the [[Pisa Baptistry]] in the [[Piazza dei Miracoli]]]]

== History following construction ==
Between 1589 and 1592,<ref>Some contemporary sources speculate about the exact date; e.g. Rachel Hilliam gives 1591 (''Galileo Galilei: Father of Modern Science'', The Rosen Publishing Group, 2005, p. 101).</ref> [[Galileo Galilei]], who lived in Pisa at the time, is said to have [[Galileo's Leaning Tower of Pisa experiment|dropped two cannonballs]] of different [[mass]]es from the tower to demonstrate that their speed of descent was independent of their mass, in keeping with the [[scientific law]] of [[free fall]]. The primary source for this is the biography ''Racconto istorico della vita di Galileo Galilei (Historical Account of the Life of Galileo Galilei)'', written by Galileo's pupil and secretary [[Vincenzo Viviani]] in 1654, but only published in 1717, long after his death.<ref>{{cite news |url=http://www.hindu.com/seta/2005/06/30/stories/2005063000351500.htm |archive-url=https://web.archive.org/web/20051102091621/http://www.hindu.com/seta/2005/06/30/stories/2005063000351500.htm |url-status=dead |archive-date=2 November 2005 |title=Sci Tech: Science history: setting the record straight |date=30 June 2005 |newspaper=[[The Hindu]] |access-date=5 May 2009}}</ref><ref>[http://brunelleschi.imss.fi.it/itineraries/biography/VincenzoViviani.html Vincenzo Viviani] {{Webarchive|url=https://web.archive.org/web/20160206182251/http://brunelleschi.imss.fi.it/itineraries/biography/VincenzoViviani.html |date=6 February 2016 }} on museo galileo</ref>

During [[World War II]], the [[Allies of World War II|Allies]] suspected that the Germans were using the tower as an observation post. Leon Weckstein, a [[U.S. Army]] [[sergeant]] sent to confirm the presence of German troops in the tower, was impressed by the beauty of the cathedral and its campanile, and thus refrained from ordering an [[artillery]] strike, sparing it from destruction.<ref name="tilt">{{cite book|last=Shrady|first=Nicholas |date=October 7, 2003|title=Tilt: a skewed history of the Tower of Pisa |publisher=[[Simon & Schuster]]|isbn=978-0-74-322926-5 |oclc=52086370|via=[[Archive.org]]|url-access=registration|pages=147–152 |url=https://archive.org/details/tiltskewedhistor0000shra/mode/2up|access-date=28 September 2023 }}</ref><ref>{{cite news |url=https://www.theguardian.com/theguardian/2000/jan/13/features11.g23 |title=Why I spared the Leaning Tower of Pisa |newspaper=The Guardian |date=12 January 2000 |access-date=19 July 2012 |archive-date=9 May 2014 |archive-url=https://web.archive.org/web/20140509082459/http://www.theguardian.com/theguardian/2000/jan/13/features11.g23 |url-status=live }}</ref>

Numerous efforts have been made to restore the tower to a vertical orientation or at least keep it from falling over. Most of these efforts failed; some worsened the tilt. On 27 February 1964, the government of Italy requested aid in preventing the tower from toppling. It was, however, considered important to retain the current tilt, due to the role that this element played in promoting the tourism industry of Pisa.<ref>{{cite news |url=https://query.nytimes.com/gst/fullpage.html?res=9B0DE5DE153EF932A35752C1A961948260 |work=The New York Times |title=Securing the Lean In Tower of Pisa |date=1 November 1987 |access-date=17 February 2017 |archive-date=14 February 2009 |archive-url=https://web.archive.org/web/20090214004751/http://query.nytimes.com/gst/fullpage.html?res=9B0DE5DE153EF932A35752C1A961948260 |url-status=live }}</ref>

Starting in 1993, 870 tonnes of lead [[counterweights]] were added, which straightened the tower slightly.<ref name= time2001>{{cite news |url=http://content.time.com/time/magazine/article/0,9171,1000167,00.html |magazine=[[Time (magazine)|TIME Magazine]] |title=Tipping the Balance |date=25 June 2001 |access-date=30 May 2020 |archive-date=23 November 2020 |archive-url=https://web.archive.org/web/20201123212536/http://content.time.com/time/magazine/article/0,9171,1000167,00.html |url-status=live }}</ref>

The tower and the neighbouring [[cathedral]], [[baptistery]], and cemetery are included in the [[Piazza del Duomo, Pisa|Piazza del Duomo]] [[World Heritage Site|UNESCO World Heritage Site]], which was declared in 1987.<ref>{{cite web |title=Piazza del Duomo, Pisa |url=https://whc.unesco.org/en/list/395 |publisher=[[UNESCO]] World Heritage Centre |access-date=8 August 2016 |archive-date=2 September 2016 |archive-url=https://web.archive.org/web/20160902082028/http://whc.unesco.org/en/list/395 |url-status=live }}</ref>

The tower was closed to the public on 7 January 1990,<ref name=closed1990>{{cite news |url=http://news.bbc.co.uk/onthisday/hi/dates/stories/january/7/newsid_4037000/4037997.stm |title=BBC on this day: 1990: Leaning Tower of Pisa closed to public |work=BBC News |access-date=29 April 2020 |archive-date=20 February 2020 |archive-url=https://web.archive.org/web/20200220055707/http://news.bbc.co.uk/onthisday/hi/dates/stories/january/7/newsid_4037000/4037997.stm |url-status=live }}</ref> after more than two decades of stabilisation studies and spurred by the abrupt collapse of the [[Civic Tower (Pavia)|Civic Tower of Pavia]] in 1989.<ref name="nytimes1989">{{cite news |last=Hofman |first=Paul |date=30 July 1989 |title=Italy's Endangered Treasures |url=https://www.nytimes.com/1989/07/30/travel/italy-s-endangered-treasures.html |work=[[New York Times]] |location=New York |access-date=29 April 2020 |archive-date=9 November 2020 |archive-url=https://web.archive.org/web/20201109042526/https://www.nytimes.com/1989/07/30/travel/italy-s-endangered-treasures.html |url-status=live }}</ref><ref name="latimes1989">{{cite news |last=Montalbo |first=William D |date=18 March 1989 |title=900-Year-Old Bell Tower Collapses in Italy; Three Killed |url=https://www.latimes.com/archives/la-xpm-1989-03-18-mn-119-story.html |work=[[Los Angeles Times]] |location=Los Angeles |access-date=29 April 2020 |archive-date=30 November 2020 |archive-url=https://web.archive.org/web/20201130083223/https://www.latimes.com/archives/la-xpm-1989-03-18-mn-119-story.html |url-status=live }}</ref> The bells were removed to relieve some weight, and cables were cinched around the third level and anchored several hundred meters away, and residences in the path of a potential collapse were vacated. The selected method for preventing the collapse of the tower was to slightly reduce its tilt to a safer angle by removing {{convert|38|m3|0|abbr=off}} of soil from underneath the raised end. The tower's tilt was reduced by {{convert|45|cm|in|frac=2|abbr=off}}, returning to its 1838 position. After a decade of corrective reconstruction and stabilization efforts, the tower was reopened to the public on 15 December 2001, and was declared stable for at least another 300 years.<ref name= time2001/> In total, {{convert|70|metric ton|short ton}} of soil were removed.<ref name=stabilized>{{cite news |last=Duff |first=Mark |url=http://news.bbc.co.uk/2/hi/europe/7423957.stm |title=Europe &#124; Pisa's leaning tower 'stabilised' |work=BBC News |date=28 May 2008 |access-date=5 May 2009 |archive-date=20 April 2013 |archive-url=https://web.archive.org/web/20130420121215/http://news.bbc.co.uk/2/hi/europe/7423957.stm |url-status=live }}</ref>

After a phase (1990–2001) of structural strengthening,<ref>[http://www.ingenia.org.uk/ingenia/articles.aspx?Index=322 A profile of an engineer employed to straighten the tower] {{Webarchive|url=https://web.archive.org/web/20120127115940/http://www.ingenia.org.uk/ingenia/articles.aspx?Index=322 |date=27 January 2012 }} ''Ingenia'', March 2005</ref> the tower has been undergoing gradual surface restoration to repair visible damage, mostly corrosion and blackening. These are particularly pronounced due to the tower's age and its exposure to wind and rain.<ref>{{Cite web |url=http://piazza.opapisa.it/index_pdm.html |title=Restoration work is mentioned at the official website of the square |access-date=14 May 2007 |archive-url=https://web.archive.org/web/20091025182652/http://piazza.opapisa.it/index_pdm.html |archive-date=25 October 2009 |url-status=dead }}</ref> In May 2008, engineers announced that the tower had been stabilized such that it had stopped moving for the first time in its history. They stated that it would be stable for at least 200 years.<ref name=stabilized />

A ceremony for the 850th anniversary of the laying of the foundation stone was held on 9 August 2023.<ref>{{cite news |title=La Torre Pendente di Pisa compie 850 anni |url=https://www.tgcom24.mediaset.it/cronaca/torre-di-pisa-compie-850-anni_68169958-202302k.shtml |access-date=8 August 2023 |agency=tgcom24.mediaset.it |publisher=tgcom24.mediaset.it |date=8 August 2023}}</ref>

<gallery mode="packed"| heights="315px">
File:Leaning_Tower_of_Pisa_in_the_1890s.jpg|Leaning Tower of Pisa in the 1890s<ref>{{Cite web |url=https://coololdphotos.com/leaning-tower-of-pisa-in-the-1890s/ |title=Leaning Tower of Pisa in the 1890s |last=Tom |date=2015-05-06 |website=Cool Old Photos |language=en-US |access-date=2019-03-05 |archive-date=6 March 2019 |archive-url=https://web.archive.org/web/20190306043931/https://coololdphotos.com/leaning-tower-of-pisa-in-the-1890s/ |url-status=live }}</ref>
File:Plaque galileo.jpg|Plaque in memory of [[Galileo Galilei]]'s experiments
File:Pisa schiefer turm gewichte 1998 01.jpg|Temporary lead counterweights, 1998
File:Pisa Cathedral & Leaning Tower of Pisa.jpg|The [[Pisa Baptistery|Baptistery]] (in the foreground), the [[Pisa Cathedral|Cathedral]] (in the middleground), and the Leaning Tower of Pisa (in the background)
</gallery>

== Earthquake survival ==
The tower has survived at least four strong [[earthquake]]s since 1280. A 2018 engineering investigation concluded that the tower withstood the tremors because of dynamic [[soil-structure interaction]]: the height and stiffness of the tower combined with the softness of the foundation soil influences the tower's vibrational characteristics in such a way that it does not [[Mechanical resonance#Resonance disaster|resonate]] with [[Strong ground motion|earthquake ground motion]]. The same soft soil that caused the leaning and brought the tower to the verge of collapse helped to prevent significant destruction in the event of an earthquake.<ref>{{cite web |url=https://www.sciencedaily.com/releases/2018/05/180509105004.htm |title=500-year-old Leaning Tower of Pisa mystery unveiled by engineers |website=ScienceDaily |date=9 May 2018 |access-date=22 November 2018 |archive-date=22 November 2018 |archive-url=https://web.archive.org/web/20181122172017/https://www.sciencedaily.com/releases/2018/05/180509105004.htm |url-status=live }}</ref>

== Technical information ==
[[File:Leaning Tower of Pisa Cyark.png|thumb|right|300px|An elevation image of the Leaning Tower of Pisa cut with [[3D Scanner|laser scan]] data from a [[University of Ferrara]]/[[CyArk]] research partnership, with source image accurate down to {{convert|5|mm|in|frac=16|abbr=on}}.]]

* Elevation of Piazza del Duomo: about 2 metres (6 feet, DMS)
* Height from the ground floor: {{convert|55.863|m|ftin|frac=16|abbr=on}},<ref name=":0">{{Cite journal |date=1952 |title=2051? |url=https://books.google.com/books?id=Ma1UAAAAMAAJ |journal=The Michigan Architect and Engineer |language=en |volume=27 |pages=17 |access-date=5 August 2019 |archive-date=2 July 2020 |archive-url=https://web.archive.org/web/20200702140338/https://books.google.com/books?id=MA1uAAAAMAAJ |url-status=live }}</ref> 8 stories<ref>{{Cite journal|last=Burland|first=J.B.|date=2008|title=Stabilising the Leaning Tower of Pisa: the Evolution of Geotechnical Solutions|url=https://www.researchgate.net/publication/233563191|journal=[[Transactions of the Newcomen Society|Trans. Newcomen Soc.]]|volume=78|issue=2|pages=174|doi=10.1179/175035208X317657|s2cid=110178919|issn=0372-0187}}</ref>
* Height from the foundation floor: {{convert|58.36|m|ftin|frac=2|abbr=on}}<ref>{{Cite book |url=https://books.google.com/books?id=PHGn0tDuNFkC&pg=PA44 |title=Art and History of Pisa |last=Valdes |first=Giuliano |date=1994 |publisher=Casa Editrice Bonechi |isbn=9788880290247 |pages=44 |language=en |access-date=5 August 2019 |archive-date=9 August 2021 |archive-url=https://web.archive.org/web/20210809134031/https://books.google.com/books?id=PHGn0tDuNFkC&pg=PA44 |url-status=live }}</ref>
* Outer diameter of base: {{convert|15.484|m|ftin|frac=16|abbr=on}}<ref name=":0" />
* Inner diameter of base: {{convert|7.368|m|ftin|frac=16|abbr=on}}<ref name=":0" />
* Angle of slant: 3.97 degrees<ref name=rawstory /> or {{convert|3.9|m|ftin|abbr=on}} from the vertical<ref name="ReferenceA">tan(3.97 degrees) * (55.86m + 56.70m)/2 = 3.9m</ref>
* Weight: {{Convert|14700|metric ton|short ton|}}<ref>{{Cite book |url=https://books.google.com/books?id=mKjCPPef7jYC&pg=PA124 |title=Site Engineering for Landscape Architects |last1=Strom |first1=Steven |last2=Nathan |first2=Kurt |last3=Woland |first3=Jake |last4=Lamm |first4=David |date= 2009 |publisher=John Wiley and Sons |isbn=9780471695493 |pages=124 |language=en |access-date=5 August 2019 |archive-date=9 August 2021 |archive-url=https://web.archive.org/web/20210809134029/https://books.google.com/books?id=mKjCPPef7jYC&pg=PA124 |url-status=live }}</ref>
* Thickness of walls at the base: {{convert|2.44|m|ftin|frac=2|abbr=on}}
* Total number of bells: 7, tuned to [[musical scale]],<ref>{{Cite book|url=https://archive.org/details/in.ernet.dli.2015.96606|title=The Real Europe Pocket Guide-book: Number 10 of the 'Black's Blue Books'|last=Black|first=William Harman|date=1920|publisher=Brentanos|pages=[https://archive.org/details/in.ernet.dli.2015.96606/page/n414 360]|language=en|oclc=316943604}}</ref> clockwise:{{Citation needed|date=August 2019}}
** 1st bell: L'Assunta, cast in 1654 by [[Giovanni Pietro Orlandi]], weight {{convert|3620|kg|0|abbr=on}}
** 2nd bell: Il Crocifisso, cast in 1572 by [[Vincenzo Possenti]], weight {{convert|2462|kg|0|abbr=on}}
** 3rd bell: San Ranieri, cast in 1719–1721 by [[Giovanni Andrea Moreni]], weight {{convert|1448|kg|0|abbr=on}}
** 4th bell: La Terza (1st small one), cast in 1473, weight {{convert|300|kg|0|abbr=on}}
** 5th bell: La Pasquereccia or La Giustizia, cast in 1262<ref>{{Cite book |url=https://archive.org/details/rivieraorcoastf01blacgoog |title=The Riviera, Or The Coast from Marseilles to Leghorn: Including the Interior Towns of Carrara, Lucca, Pisa and Pistoia |last=Black |first=Charles Bertram |date=1898 |publisher=A. & C. Black |pages=[https://archive.org/details/rivieraorcoastf01blacgoog/page/n210 148] |language=en |oclc=18806463}}</ref> by [[Lotteringo]], weight {{convert|1014|kg|0|abbr=on}}
** 6th bell: Il Vespruccio (2nd small one), cast in the 14th century and again in 1501 by [[Nicola di Jacopo]], weight {{convert|1000|kg|0|abbr=on}}
** 7th bell: [[Carlo Antonio Dal Pozzo|Dal Pozzo]], cast in 1606 and again in 2004, weight {{convert|652|kg|0|abbr=on}}<ref>{{cite web |url=http://www.endex.com/gf/buildings/ltpisa/ltpinfo/BellsFile/DalPozzo.htm |title=Leaning Tower of Pisa: 1920s Photo of Dal Pozzo |publisher=www.endex.com |access-date=9 August 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100418050651/http://www.endex.com/gf/buildings/ltpisa/ltpinfo/BellsFile/DalPozzo.htm |archive-date=18 April 2010 }}</ref>
* Number of steps to the top: 296<ref>{{cite book |last=Davies |first=Andrew |title=The Children's Visual World Atlas |publisher=The Fog Press |year=2005 |location=Sydney, Australia |isbn=1740893174}}</ref>

About the 5th bell: The name ''Pasquareccia'' comes from ''Easter'', because it used to ring on Easter day. However, this bell is older than the bell-chamber itself, and comes from the tower Vergata in ''Palazzo Pretorio'' in Pisa, where it was called ''La Giustizia'' (The Justice). The bell was tolled to announce executions of criminals and traitors, including [[Ugolino della Gherardesca|Count Ugolino]] in 1289.<ref name="Ugolino">{{cite web |url=http://www.luccaturismo.com/umutesiadd.asp?id=56 |title=Torre pendente |access-date=19 March 2008 |publisher=Lucca turismo |language=it |archive-date=8 April 2008 |archive-url=https://web.archive.org/web/20080408070258/http://www.luccaturismo.com/umutesiadd.asp?id=56 |url-status=live }}</ref> A new bell was installed in the bell tower at the end of the 18th century to replace the broken ''Pasquareccia''.{{Citation needed|date=August 2019}}
{{clear}}

The circular shape and great height <!-- (currently {{convert|55.86|m|ftin|2|abbr=on}} on the lowest side and {{convert|56.67|m|ftin|2|abbr=on}} m on the highest) -->of the campanile were unusual for their time, and the crowning belfry is stylistically distinct from the rest of the construction. This belfry incorporates a {{convert|14|cm|in|frac=2|abbr=on}} correction for the inclined axis below. The siting of the campanile within the Piazza del Duomo diverges from the axial alignment of the cathedral and baptistery of the Piazza del Duomo.{{Citation needed|date=August 2019}}

== ''Guinness World Records'' ==
Two German churches have challenged the tower's status as the world's most lopsided building: the 15th-century square [[Leaning Tower of Suurhusen]] and the 14th-century bell tower of the [[Oberkirche, Bad Frankenhausen|Oberkirche]] in the town of [[Bad Frankenhausen#Sights|Bad Frankenhausen]].<ref>''Sunday Telegraph'' no. 2,406, 22 July 2007</ref> ''[[Guinness World Records]]'' measured the Pisa and Suurhusen towers, finding the former's tilt to be 3.97 degrees.<ref name=rawstory>{{cite web |url=https://en.trend.az/world/other/1072751.html |title=German steeple beats Leaning Tower of Pisa into Guinness book |date=9 November 2007 |agency=AFP |website=Trend News Agency |url-status=live |archive-url=https://web.archive.org/web/20090504212210/http://rawstory.com/news/afp/German_steeple_beats_Leaning_Tower__11082007.html |archive-date=4 May 2009}}</ref> In June 2010, ''Guinness World Records'' certified the [[Capital Gate]] building in [[Abu Dhabi]], [[UAE]] as the "World's Furthest Leaning Man-made Tower";<ref name=cnnnews>{{cite news |url=http://www.cnn.com/2010/WORLD/meast/06/06/uae.leaning.tower/index.html?hpt=C2 |title=Not so fast, Pisa! UAE lays claim to world's furthest leaning tower |publisher=CNN news |access-date=6 June 2010 |date=7 June 2010 |archive-date=8 June 2010 |archive-url=https://web.archive.org/web/20100608100846/http://www.cnn.com/2010/WORLD/meast/06/06/uae.leaning.tower/index.html?hpt=C2 |url-status=live }}</ref> it has an 18-degree slope, almost five times more than the Tower of Pisa, but was deliberately engineered to slant. The [[Puzzling World#The Leaning Tower of Wanaka|Leaning Tower of Wanaka]] in [[Wānaka]], [[New Zealand]], also deliberately built, leans at 53 degrees to the ground.<ref>[http://www.puzzlingworld.co.nz/attractions.html 'Leaning and tumbling towers'] {{Webarchive|url=https://web.archive.org/web/20110730120948/http://www.puzzlingworld.co.nz/attractions.html |date=30 July 2011 }} on Puzzling World website, viewed 30 July 2011</ref>

== Gallery ==
<gallery mode="packed" heights="200">
File:Lightmatter pisa.jpg|View looking up
File:Leaning tower door.JPG|Entrance door to the bell tower
File:Leaning tower loggiati.jpg|External [[loggia]]
File:Leaning tower staircase 6th floor.jpg|Inner staircase from sixth to seventh floor
File:Leaning tower staircase 7th floor.JPG|Inner staircase from seventh to eighth (the top) floor
File:Leaning tower staircase 8th floor.JPG|View from the top
File:View, looking down from top of Leaning Tower of Pisa.jpg|View, looking down from the top
File:The Leaning Tower of Pisa SB.jpeg|Leaning Tower of Pisa in 2013
File:Tower of Pisa - push.jpg|Tourist in a common pose at Tower of Pisa, June 2009
</gallery>

== See also ==
* [[Leaning Temple of Huma]]
* [[List of leaning towers]]
** [[Leaning Tower of Niles]], a replica of the Tower of Pisa
** [[Leaning Tower of Zaragoza]], was a famous European leaning tower
** [[Great Mosque of al-Nuri (Mosul)]], an ancient leaning tower that stood until 2017; reconstruction efforts are currently underway
* [[List of tallest structures built before the 20th century]]
* [[Round tower (disambiguation)]], for other types of round towers
* [[List of buildings in King's Lynn#Greyfriars Tower|The Greyfriars Tower]], the remains of a Franciscan monastery in King's Lynn, nicknamed "The Leaning Tower of Lynn"
* [[Torre delle Milizie]], a tilting medieval tower in Rome
* [[Tour de Pise]], a rock dome in Antarctica, was named after this tower

== References ==
{{reflist}}

== External links ==
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* {{Official website|https://www.opapisa.it/en/|name=Opera della Primaziale Pisana}}{{snd}}official site {{in lang|en|it}}
* [https://web.archive.org/web/20111223085312/http://archive.cyark.org/piazza-del-duomo-pisa-intro Piazza dei Miracoli digital media archive] ([[Creative Commons]]{{snd}}licensed photos, laser scans, panoramas), data from a [[University of Ferrara]]/[[CyArk]] research partnership, includes 3D scan data from the Leaning Tower of Pisa.
* {{Structurae|id=20002483|title=Leaning Tower of Pisa}}

{{Pisa landmarks}}
{{Landmarks of Tuscany}}
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[[Category:1372 establishments in Europe]]
[[Category:Bell towers in Italy]]
[[Category:Buildings and structures completed in 1372]]
[[Category:Inclined towers]]
[[Category:Round towers]]
[[Category:Romanesque architecture in Pisa]]
[[Category:Tourist attractions in Pisa]]
[[Category:Towers completed in the 14th century]]
[[Category:Towers in Pisa]]
[[Category:World Heritage Sites in Italy]]
[[Category:Christian bell towers]]