Mines Of Tunnel Network, Catacombes De Paris, Paris, France

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 under the "Saints Innocents" church from 1130, this burial ground, filling the land between today's 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 Parisan Les Halles marketplace, 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 to the inside of the cemetery walls. By the end of the 18th century, the central burial ground was a two metre high mound of earth filled with centuries of Parisian dead from disease, famine, and wars, plus the remains from the Hôtel-Dieu hospital and the Morgue; other Parisian parishes had their own burial grounds, but the conditions in Les Innocents cemetery were by far the worst.
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.