Editing Catacombs of Paris (section)

===The future ossuary: Paris's former mines===
{{further|Mines of Paris}}
[[File:Plan paris gerards1908 jms.jpg|thumb|Map of former underground mine exploitations in Paris (1908)]]
Much of the Left Bank area rests upon rich [[Lutetian limestone]] deposits. This stone built much of the city, but it was extracted in suburban locations away from any habitation. Because of the post 12th-century haphazard mining technique of digging wells down to the deposit and extracting it horizontally until depletion, many of these (often illicit) mines were uncharted, and when depleted, often abandoned and forgotten. Paris had annexed its suburbs many times over the centuries, and by the 18th century many of its arrondissements (administrative districts) were or included previously mined territories.<ref>{{Cite web|url=https://dailycampus.com/stories/2016/9/7/weird-wednesday-the-mines-of-paris|title=Weird Wednesday: The mines of Paris|archive-url=https://web.archive.org/web/20200729230442/https://dailycampus.com/stories/2016/9/7/weird-wednesday-the-mines-of-paris|archive-date=2020-07-29}}</ref>

The undermined state of the Left Bank was known to architects as early 17th-century construction of the [[Val-de-Grâce]] hospital (most of its building expenses were due to its foundations), but a series of mine cave-ins beginning 1774 with the collapse of a house along the "rue d'Enfer" (near today's crossing of the Avenue Denfert-Rochereau and the [[boulevard Saint-Michel]]) caused King [[Louis XVI]] to name a commission to investigate the state of the Parisian underground. This resulted in the creation of the ''inspection Générale des Carrières'' (Inspection of Mines) service.{{Citation needed|date=January 2021}}