One of the most eye-popping sights of Paris, the catacombs represent a network of labyrinthine tunnels, first excavated in the Roman period, that now house the remains of over 6 million burials removed here from the various overcrowded cemeteries and charnel houses all over Paris in the late 18th and early 19th centuries. Well worth a visit: the atmosphere is suitably morbid and gloomy (without being too scary), the dark tunnels containing neatly stacked piles of skulls and long bones. There is a limit to the number of visitors allowed within the Catacombs at one time (200 persons). So, if you arrive just after opening, you must wait until someone exits, approximately 45–60 minutes, before anyone is admitted. Steep stairwell on the exit of the catacombs. Can be challenging for the elderly or the unfit. Tickets can be purchased online which allows you pick a date & time and to skip the long line.

The Catacombs of Paris are underground ossuaries in Paris, France, which hold the remains of more than six million people. Built to consolidate Paris's ancient stone quarries, they extend south from the Barrière d'Enfer former city gate. The ossuary was created as part of the effort to eliminate the effects of the city's overflowing cemeteries. Preparation work began shortly after a 1774 series of basement wall collapses around the Holy Innocents' Cemetery added a sense of urgency to the cemetery-eliminating measure, and from 1788, nightly processions of covered wagons transferred remains from most of Paris's cemeteries to a mine shaft opened near the Rue de la Tombe-Issoire. 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 1874. Since 2013, the Catacombs have numbered among the fourteen City of Paris Museums managed by Paris Musées. 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.