The ossuary remained largely forgotten until it became a novelty-place for concerts and other private events in the early 19th century; after further renovations and the construction of accesses around Place Denfert-Rochereau , it was opened to public visitation from Although the ossuary comprises only a small section of the underground mines of Paris , Parisians often refer to the entire tunnel network as the catacombs. Paris 's earliest burial grounds were to the southern outskirts of the Roman-era Left Bank city.
Thus, instead of burying its dead away from inhabited areas as usual, the Paris Right Bank settlement began with cemeteries near its centre.
The most central of these cemeteries, a burial ground around the 5th-century Notre-Dame-des-Bois church, became the property of the Saint-Opportune parish after the original church was demolished by the 9th-century Norman invasions. When it became its own parish associated with the church of the " Saints Innocents " from , this burial ground, filling the land between the present rue Saint-Denis , rue de la Ferronnerie , rue de la Lingerie and the rue Berger , had become the city's principal cemetery.
By the end of the same century, Saints Innocents was neighbour to the principal Parisian marketplace Les Halles , and already filled to overflowing. To make room for more burials, the long-dead were exhumed and their bones packed into the roofs and walls of "charnier" galleries built inside the cemetery walls. By the end of the 18th century, the central burial ground was a two-metre-high 6. A series of ineffective decrees limiting the use of the cemetery did little to remedy the situation, and it was not until the late 18th century that it was decided to create three new large-scale suburban burial grounds on the outskirts of the city, and to condemn all existing parish cemeteries within city limits.
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.
