Editing St. Peter's Basilica (section)

====Bramante and Sangallo, 1506 and 1513====
[[File:Caradosso Foppa, View of Saint Peter's (reverse), 1506, NGA 44669.jpg|thumb|upright|1506 medal by [[Cristoforo Foppa]] depicting Bramante's design, including two of the four flanking smaller domes<ref>{{cite book |last1=De la Croix |first1=Horst |last2=Tansey |first2=Richard G. |last3=Kirkpatrick |first3=Diane |title=Gardner's Art Through the Ages |date=1991 |publisher=Thomson/Wadsworth |isbn=0-15-503769-2 |edition=9th |page=[https://archive.org/details/gardnersartthrou00gard/page/641 641] |url-access=registration |url=https://archive.org/details/gardnersartthrou00gard/page/641}}</ref>{{Failed verification|date=April 2025|reason=The reference to page 641 is incorrect to the linked source, which only has 612 total pages, but what appear to be two additional domes on the left and right sides of the image are instead just half-domes at the ends of the transept.}}]]
The dome of the Pantheon stands on a circular wall with no entrances or windows except a single door. The whole building is as high as it is wide. Its dome is constructed in a single shell of [[concrete]], made light by the inclusion of a large amount of the volcanic stones tuff and pumice. The inner surface of the dome is deeply [[coffering|coffered]] which has the effect of creating both vertical and horizontal ribs while lightening the overall load. At the summit is an ocular opening {{convert|8|m|ft}} across which provides light to the interior.<ref name=BF/>

Bramante's plan for the dome of St. Peter's (1506) follows that of the Pantheon very closely, and like that of the Pantheon, was designed to be constructed in [[Tufa]] Concrete for which he had rediscovered a formula. With the exception of the lantern that surmounts it, the profile is very similar, except that in this case, the supporting wall becomes a [[drum (architecture)|drum]] raised high above ground level on four massive piers. The solid wall, as used at the Pantheon, is lightened at St. Peter's by Bramante piercing it with windows and encircling it with a [[peristyle]].

In the case of [[Florence Cathedral]], the desired visual appearance of the pointed dome existed for many years before [[Filippo Brunelleschi|Brunelleschi]] made its construction feasible.{{NoteTag|The dome of Florence Cathedral is depicted in a fresco at [[Santa Maria Novella]] that pre-dates its building by about 100 years.}} Its double-shell construction of bricks locked together in a herringbone pattern (re-introduced from Byzantine architecture), and the gentle upward slope of its eight stone ribs made it possible for the construction to take place without the massive wooden formwork necessary to construct hemispherical arches. While its appearance, with the exception of the details of the lantern, is entirely Gothic, its engineering was highly innovative, and the product of a mind that had studied the huge vaults and remaining dome of Ancient Rome.<ref name=Hartt>{{Harvnb|Hartt|2006}}</ref>

Sangallo's plan (1513), of which a large wooden model still exists, looks to both these predecessors. He realized the value of both the coffering at the Pantheon and the outer stone ribs at Florence Cathedral. He strengthened and extended the peristyle of Bramante into a series of arched and ordered openings around the base, with a second such arcade set back in a tier above the first. In his hands, the rather delicate form of the lantern, based closely on that in Florence, became a massive structure, surrounded by a projecting base, a [[peristyle]] and surmounted by a spire of conic form.<ref name="Fletcher 1996 p=722"/> According to [[James Lees-Milne]] the design was "too eclectic, too pernickety and too tasteless to have been a success".<ref name=JL-M/>

<gallery mode="packed" heights="190">
File:Roma S.Pietro in Vaticano (zzf).jpg|alt=Engraved image in two parts. The left side shows the exterior of the dome, and the right side shows a cross-section. The dome is constructed of a single shell, surrounded at its base by a continuous colonnade and surmounted by a temple-like lantern with a ball and cross on top.|Bramante's dome
File:Roma S.Pietro in Vaticano (zzg).jpg|alt=An engraved picture showing an immensely complex design for the façade, with two ornate towers and a multitude of windows, pilasters and pediments, above which the dome rises looking like a three-tiered wedding cake.|Sangallo's design
File:Speculum Romanae Magnificentiae- Elevation Showing the Exterior of Saint Peter's Basilica from the South as Conceived by Michelagelo (Published in 1569) MET DT203424.jpg|alt=This engraving shows the chancel end of the building much as it was built, except that the dome in this picture is completely semi-circular, not ovoid|The engraving by Stefan du Pérac was published in 1569, five years after the death of Michelangelo.
</gallery>