CitiesFrance
Paris was quarried out of the ground it stands on. The pale Lutetian limestone that faces Notre-Dame and the Louvre came from directly underneath the city, first from open pits and then from galleries tunnelled outward as Paris grew over its own workings. By the eighteenth century the honeycomb was failing. On 17 April 1774 the rue d'Enfer collapsed into it, and Louis XVI created a state agency in 1777 whose job was to find the holes and hold the city up.
A short section of the old quarry network, filled with the remains of some six million people moved out of overflowing city cemeteries from the late eighteenth century. The bones are the second use of the space. The tunnels were mine galleries first, and the ossuary exists because two problems, unstable voids and overfull graveyards, were solved against each other.
The cathedral begun in 1163, faced in limestone cut from beneath the city, and rebuilt after the 2019 fire. The detail visitors miss is how thoroughly it was already a reconstruction: it was stripped during the Revolution and heavily restored in the nineteenth century by Viollet-le-Duc, who added the spire that burned.
A fortress before it was a palace and a palace before it was a museum, with the medieval foundations exposed in the basement. The moat walls you can walk beside down there are the original twelfth-century keep. The glass pyramid was fiercely opposed on completion and is now the building's least controversial feature.
A cemetery of 1804 that nobody wanted to be buried in, being too far out and unconsecrated by the standards of the day. The administration solved it with marketing: they transferred the supposed remains of Molière and La Fontaine, then Abélard and Héloïse, and plot sales rose sharply. The most famous cemetery in the world was a property play.
A royal chapel of the 1240s built to house relics, with walls that are almost entirely stained glass. It was engineered as a reliquary at architectural scale. Louis IX paid far more for the relics themselves than for the building constructed to hold them, which tells you the priority.
A church that became a mausoleum during the Revolution, then a church again, then a mausoleum, changing function with each swing of French politics. Foucault hung his pendulum here in 1851 to demonstrate the Earth's rotation. Its dome cracked early because the ground beneath it, like much of the Left Bank, was undermined.
A canal of 1825 built to bring fresh water into the city, running partly underground beneath the boulevards. Napoleon ordered it after repeated cholera and supply problems. The covered section exists because a later administration wanted the surface for a road, which is why the canal appears to stop and start.
A Roman amphitheatre in the fifth arrondissement, lost for centuries and found again in the 1860s during roadworks. It is now a public square where locals play boules among the tiered seating. Paris keeps a first-century arena as a neighbourhood park and barely mentions it.
The hill north of the centre, and the reason it is a hill of gypsum rather than limestone matters: it was mined so heavily for plaster that the ground beneath is exceptionally unstable. The basilica at the summit rests on deep piled foundations sunk to reach something solid. The famous artists' quarter sits on a hollowed-out hill.
One of the surviving covered arcades of the early nineteenth century, glass-roofed and lined with small shops. These were the ancestors of the department store and the shopping mall, built when the streets were filthy and unlit. Most were demolished; the ones left are a preserved retail idea two centuries old.
Paris is built out of its own basement.
The Lutetian limestone facing Notre-Dame, the Louvre and much of the older city was quarried directly beneath it. As Paris expanded, it grew over the galleries that had supplied its own stone.
A Paris street fell into the ground in 1774 and the king created an agency to stop it happening again.
On 17 April 1774 the rue d'Enfer collapsed into the forgotten quarry workings, taking houses with it. In 1777 Louis XVI established the Inspection Générale des Carrières, which has been mapping and shoring up the voids under Paris ever since.
The catacombs were mine tunnels before they were an ossuary.
The remains of around six million people were moved into disused quarry galleries from the late eighteenth century, clearing overflowing cemeteries and putting the dangerous voids to use at the same time. Two civic problems cancelled each other out.
The world's most famous cemetery was a failing business that faked its way to success.
Père Lachaise opened in 1804 and sold badly. The administration transferred remains attributed to Molière, La Fontaine, Abélard and Héloïse into the grounds, publicised it, and plot sales climbed. It was a marketing campaign with bodies.
Notre-Dame's spire that burned in 2019 was a nineteenth-century addition.
The cathedral was stripped during the Revolution and extensively rebuilt by Viollet-le-Duc in the 1800s. The spire lost in the fire was his, not medieval, which complicates what exactly was being mourned.
Montmartre is hollow.
The hill is gypsum and was mined heavily for plaster, which is where plaster of Paris gets its name. The workings left the ground so unstable that Sacré-Cœur had to be founded on deep piles driven down to solid material.
There is a Roman amphitheatre in Paris and it is used as a park.
The Arènes de Lutèce was buried and forgotten for centuries, turned up again during roadworks in the 1860s, and is now an ordinary neighbourhood square where people play boules in a first-century arena.
This page is a whole city. The app does the block you’re standing on.
This is what Pinaround does at city scale. Tap the button for the corner you’re actually on.