Catacombs of Paris

Paris was built partly from limestone quarried beneath it, leaving hundreds of kilometres of tunnel under the southern city. By the 1780s the cemeteries were so overfull that they were a public health emergency, and the decision was taken to empty them into the quarries: bones were moved by night over decades from Les Innocents and other burial grounds, and rather than being tipped in they were arranged, stacked into walls of femurs and skulls in patterns, with plaques recording which cemetery each section came from. Around six million people's remains lie there. A route of about a kilometre and a half is open, twenty metres below the street.

What you actually see

• The bone walls - femurs and skulls stacked into patterned facings.
• The cemetery plaques - markers recording where each section came from.
• The quarry tunnels - the limestone workings the city was built from.
• The inscriptions - carved verses and warnings along the route.

When to go

Year-round; the temperature underground stays around fourteen degrees whatever the season. Booking a timed ticket online is close to essential, as walk-up queues can run for hours.

Honest expectations

Numbers underground are capped, so unbooked queues are long. The route involves a hundred and thirty steps down and a hundred and twelve up, and is unsuitable for limited mobility or claustrophobia. Off-route tunnels are illegal to enter and policed.

Nearby

Montparnasse lies north; the Latin Quarter is northeast.