Paris’s famous catacombs date back to the late 18th century, when the city’s overcrowded graveyards were beginning to contaminate the water supply. To stop the spread of disease the authorities came up with the idea of exhuming the graves and moving the bones of the long-deceased to disused limestone quarries. The 1.6-kilometre network of underground passages has now become one of the city’s most unlikely tourist attractions, with thousands of visitors every year queuing patiently to see the stacks of bones that line the catacombs.

The bones are arranged according to type, with skulls in one place, femurs in another, and so on, forming patterns that are strangely artistic in their eerie beauty. Dotted amongst the skeletons, some of which date back to the French Revolution, are memorial plaques, providing a gentle reminder that these are real human remains and not some fantastical flight of fancy.

Among the thought-provoking features pointed out on the audio tour are the wall carvings known as the Sculptures of Decure, created in 1777 by a quarry inspector who came to an unfortunate end when he fell through a sinkhole on an upper level. The Fountain of Samaritan, a natural spring surrounded by a wall of bones, and the Sepulchral Lamp, which provided light for the quarrymen to work by, are other points of interest.

It’s easy to miss the concealed entrance to the catacombs on the Place Denfert-Rochereau, but at busy times the queue gives it away! Once you get inside, allow around an hour to explore the network of tunnels. The walkways and stairs can be slippery, so choose footwear with a good grip, and take an extra layer of clothing to stop you from shivering underground.

The Paris Catacombs are open every day except Mondays. Children under 14 years of age must be accompanied by an adult. The elderly and those with limited mobility might find it a challenge so, if in doubt, check before you enter. The location is served by public transport and there is pay parking nearby.