Catacombs of Paris

Hidden beneath the 14th arrondissement, the Catacombs of Paris, France are one of the city's most haunting attractions — an underground ossuary holding the remains of over six million people. Their history reveals why and when the site was built: in the late 18th century, overflowing cemeteries and collapsing limestone quarries sparked a public health crisis, so from 1786 the city began transferring bones into disused mine galleries. The work was led by Charles-Axel Guillaumot, the quarry inspector credited as the man who built the Catacombs of Paris. The entrance sits on Place Denfert-Rochereau, and getting here is easy — the Denfert-Rochereau stop on Metro Line 4 and RER B drops you at the location, from where 131 steps lead down into the earth.

Below ground, the interior is unforgettable: dimly lit Paris Catacombs tunnels lined with stacked skulls and femurs, engraved poems, and the famous "Empire of the Dead" inscription. A Paris Catacombs tour along the 1.5 km circuit takes about an hour, and since the underground passages stay cool year-round, the unofficial dress code is warm layers and comfortable shoes. The attraction is open Tuesday to Sunday, with opening hours running from morning to early evening and last admission well before closing, so check the schedule before your visit. French Catacombs tickets sell out fast, as only a limited number of guests enter at once, so advance booking is the smartest way to explore one of the most extraordinary places in Paris.