Beneath the sidewalks of Paris lie filled ditches, 17th-century vaults, Gothic ossuaries, and tombstones transformed into cobblestones. Here’s how to find them, street by street, stair by stair.
Beneath the sidewalks of Paris lie filled ditches, 17th-century vaults, Gothic ossuaries, and tombstones transformed into cobblestones. Here’s how to find them, street by street, stair by stair.
One can easily imagine Paris hidden behind padlocked gates, reserved for a few insiders equipped with headlamps. This is partly false. A good half of the buried treasures of the capital can be approached without permission: a steep staircase climbing an old rampart path, a low door at the back of a church, a subway platform where 17th-century vaults emerge.
However, one must be willing to take their time. Urban wandering is almost a profession, with its tricks: looking up, stopping abruptly in the middle of the sidewalk, pushing open a slightly ajar door, preferring one street over its neighbor for no valid reason. The hurried passerby sees nothing; the flâneur sees everything—and wandering, of course, takes time.
In the following pages, we follow concrete routes: the filled-in ditches of Charles V's wall, the remnants of Philippe Auguste absorbed by the city, the "cagnards" along the Seine rediscovered by the engineers of the metro, a 13th-century crypt that long served as a banana ripening room, Gothic ossuaries, gravestones turned into cobblestones.
Nota Bene: the charm of these places lies precisely in the fact that their access is free and unmarked. Discretion and restraint are therefore essential; they are endangered species of the urban genre. The attentive visitor is the opposite of a predator: they become the vigilant witness of the place, sometimes its protector.
In the middle of the 14th century, Paris was overflowing: urban expansion had surpassed the walls of Philip Augustus, which, moreover, could no longer withstand the new war machines. A new wall, known as Charles V's wall, was therefore built. On the right bank, it describes a vast arc from the Bastille, follows the direction of the current Grands Boulevards to the Porte Saint-Denis, and then plunges towards the Seine, passing through the Place des Victoires.
The figures give an idea of the monster: 4,875 meters long, a curtain wall thirteen meters high, preceded by two moats, the largest of which, at the foot of the wall, measured thirty meters wide and eight deep - and it was filled with water. This fortification protected 275,000 Parisians before being demolished in turn in 1634, its moats filled in. Nothing remains of it... except for a few accidents of the terrain.
And this is where the game begins. At 263, Rue Saint-Denis (at the time, we are still inside the city), the narrow Passage Sainte-Foy opens, which really doesn’t look like much. Its steep staircase compensates for the elevation change with Rue Sainte-Foy, where it leads: by climbing it, you simply ascend to the walkway of the rampart. Rue Sainte-Foy was actually called Rue du Rempart.
Then, you descend a few meters to the right until you reach Rue Chénier, which leads to the parallel streets of Aboukir and Cléry. Rue d'Aboukir was formed on the embankment of the large moat during the demolition of the wall, while Rue de Cléry follows the old counter-scarp path. In just a few steps, you have crossed the wall, crossed a flooded moat, and jumped from the city to the countryside.
Nota Bene: the counter-scarp is the outer walkway of the enclosure, on the other side of the moat. The word survives in several Parisian toponyms, often where the fortifications have disappeared for centuries.
The most impressive piece of medieval rampart visible in Paris is located on Rue des Jardins-Saint-Paul: seventy meters of thick wall flanked by two towers, belonging to the enclosure of Philippe Auguste, which began in 1190. The secret of its solidity? Between the outer facing stones, a mixture of sand and rubble was poured, making the construction particularly resistant. To imagine it as it once was, one must envision it a bit taller and crenellated.
If so many fragments have survived throughout Paris, it is because urban pressure has "digested" these fortifications more than it has destroyed them: they were used as solid support points, and entire sections ended up hidden - thus preserved - at the back of a courtyard or workshop. The Cour de Rohan, accessible via Rue du Jardinet, offers a fine example: in its third small courtyard, a fragment of the enclosure forms a terrace. Until 1791, Rue du Jardinet, then a dead end, met this thick wall. At number 8 of Cour du Commerce-Saint-André, one can still see, at the back left, the base of one of the towers.
The Bastille, on the other hand, has been scattered. Quickly razed, its stones were sold to build buildings and the Pont de la Concorde. On site, a ground marking made of small square cobblestones indicates its location at the entrance of Rue Saint-Antoine, and a map at number 3 of the square shows the exact location of the fortress.
The rest is underground, or almost: in 1898, the breakthrough of the first metro line uncovered the foundations of the "Tower of Liberty," at the height of 211 and 236 Rue Saint-Antoine. Dismantled stone by stone, these remains were relocated to Square Henri-Galli, where they can still be seen. At the outlet of the Canal Saint-Martin into the Arsenal basin, on the right side towards the Seine, an entire section of wall - an old ditch wall - serves as a support for Boulevard Bourdon. And on the platform of line 5 (direction Bobigny), a few stones from the counter-scarp wall of the ditch have been left in place.
The Parisian underground is primarily a matter of water. At 284 Rue Saint-Jacques, the construction of a building in 1978 nearly proved fatal for a stone portal that served as the entrance to the Carmelite convent of the Incarnation until the Revolution: protests led to it being dismantled stone by stone and reassembled behind glass, where it can still be seen today. The small private hotel next door, built in 1796 for the sculptor François Scelles (visible at 6 Rue du Val-de-Grâce), was spared as well.
The most interesting discoveries were made during the excavation work: near the cellars of the hotel, vaulted underground pipelines were uncovered, remnants of the network that carried water from Arcueil to a fountain on Rue Saint-Jacques, known as "des Carmélites." In other words, a forgotten urban aqueduct, just a few meters beneath the feet of passersby.
On Rue de Poissy, another lesson in involuntary hydrology: the refectory of the Collège des Bernardins, founded in 1244, has a basement with ribbed vaults that were regularly flooded by the Seine. Fed up, the Bernardins filled it in 1709. It was cleared out a few decades ago, revealing the 32 strong columns on octagonal bases that support a hall measuring 80 meters long and 15 wide.
Finally, to understand how Paris is oriented in relation to water, stop at the corner of Rue des Archives and Rue des Francs-Bourgeois, in front of the old fountain designed by Jean Beausire in 1710 - it replaced a fountain from 1628 that was removed by the authorities due to unsanitary conditions. Set in stone, a plaque bears the inscription "marker" and a line of numbers: it is a reminder of Haussmann's decree of May 31, 1856, which linked the plan of Paris to the sea level measured in the harbor basin of Marseille, with the difference noted at the Pont de la Tournelle in 1719.
Some passages do not descend underground: they sink into time. Facing the Val-de-Grâce, at 277 rue Saint-Jacques, beneath one of the two pavilions flanking the chapel, begins a cobbled passage lined with wheel-stops. It ends in a dead end today, but it is the former rue des Marionnettes, which once connected rue de l'Arbalète to rue Saint-Jacques. A true fossil of the urban layout, seemingly left intact by time.
Another hidden path, another atmosphere: the impasse des Arbalétriers, at 38 rue des Francs-Bourgeois. Uneven cobblestones, posts, corbels—almost all the attributes of a medieval alley are present. It was the secondary entrance to the now-disappeared Hôtel Barbette, residence of Queen Isabeau of Bavaria in the early 15th century, and the alley then led to a field where crossbowmen trained.
Historians pinpoint here, very precisely, the assassination of Louis d'Orléans, brother of Charles VI, on November 23, 1407, by the men of Jean sans Peur, as he returned from a visit to the queen. The impasse is not really an impasse: it leads to a large courtyard, which is itself connected to rue Vieille-du-Temple. This is the logic of all these Parisian corridors—they cross, they connect, they allow one to bypass the official city.
When searching for these types of ancient shortcuts, the method is simple: look for deep doorways, coach passages whose doors are not locked, low doors pierced on the side of an impasse. Nine times out of ten, there is a second courtyard behind.
In 1642, Louis XIII ceded a piece of land located between the Notre-Dame Bridge and the Pont au Change. The only constraint imposed on the new owner, the Marquis de Gesvres, was to build a quay supported by a series of arches. This is how, in the heart of the city, a vaulted gallery opened onto the river was born, a long succession of dark passages that quickly became a hideout for pickpockets and other unsavory characters.
This construction remained until the mid-19th century. In 1860, masonry walls were built to block the openings onto the Seine, and the whole area fell into complete oblivion. Only a few engravings and a painting by the artist Hubert Robert remained to testify to its existence.
Nota Bene: the term "cagnards" refers to the vaults built at the front of a port. The word has disappeared from common language, but it precisely designates this kind of space that is half-quay, half-cellar, where goods were stored, where people sought shelter... and where one sometimes had unpleasant encounters.
This type of structure explains why Paris has so many voids beneath its quays and squares: the city built over them instead of demolishing, bricking up the openings and laying fill. Nothing truly disappears; everything loops back and is covered - until a construction project comes along to reopen the file.
Around 1921, the engineers of the subway were working on the Ivry-Villette line. While digging, they came across the old vaults along the banks of the Seine, exactly at the location of the new line. They were cluttered with rubble, pipes, and sewer outlets. They could have been demolished: at the request of the wise members of the Municipal Commission of Old Paris, they were carefully cleared and preserved.
As a result, there is an underground artwork from the 17th century integrated into the metro network in Paris. To see it, go to Châtelet, on the platform of line 7 heading towards La Courneuve, on the side of the Saint-Martin street exit: vaults slightly higher than the tunnel are visible, a walkway between the two platforms allows for better observation, and panels reproduce 18th-century engravings depicting the cagnards. The oldest element of the Parisian metro dates back to the reign of Louis XIII.
The metro has also played the role of archaeologist several times despite itself: it was the breakthrough of the first line in 1898 that revealed the foundations of the Tower of Liberty at the Bastille. The principle is always the same: you dig to go fast, and you rediscover the city of the past.
Not all discoveries have been so fortunate. In 1869, the extension works of Rue Monge uncovered the substructures of the arenas of Lutetia, an amphitheater with a stage from the early 2nd century built against the slope of Mount Sainte-Geneviève. Despite an active Society of the Arenas, the site was backfilled to install a depot for the Omnibus Company, and the construction of buildings caused a good third of it to disappear. It took the campaign led in 1883 by Victor Hugo and Victor Duruy to uncover the last remnants, which were restored in 1917-1918.
At the bedside of Saint-Eustache, on rue Montmartre, a small door topped with a coat of arms goes completely unnoticed. The coat of arms features a fish seemingly biting its own tail, and this detail tells the whole story of the place: a man made his fortune at the Halles through the fish trade.
This Parisian bourgeois was named Jean Allais; he lived in the 13th century and was the leader of the mystery players. A creditor of Philip Augustus who was going on a crusade, he requested in return the permission to collect a penny on every basket of fish sold at the Halles. Fortune came quickly, as did remorse: he undertook to build a chapel for the merchants dedicated to Saint Agnes.
Enlarged over the centuries, partially demolished, the chapel was finally razed in the 16th century under the name of Saint-Eustache, to make way for the church we know today - which remains unfinished. Its cellars, however, did not disappear: abandoned, they were converted into warehouses like many cellars in the neighborhood. A few decades ago, it was still a banana ripening room.
A curious and perceptive priest had the place cleaned up. They discovered, reused in a wall, elements from the earlier chapels: capitals and fragments of columns from the 12th, 13th, and 14th centuries. Today, exhibitions and debates are regularly organized in the Sainte-Agnès crypt, which remains the best way to enter and quietly admire the work of a repentant fishmonger.
Paris long buried its dead in the heart of the city, then moved them underground. The Square des Innocents occupies the site of the largest cemetery in the capital between the 13th and 18th centuries: when it was closed in 1780, it had swallowed two million corpses in its mass graves. Quickly saturated, it was surrounded by arcaded galleries whose attics served as ossuaries, where exhumed bones were placed to free up space. Life continued under the arcades: small shops, public writers, prostitutes, crooks. In 1786, the bones were moved to old quarries that would become the Catacombs of Denfert-Rochereau.
The only remaining ossuary in the capital is located on Rue des Prêtres-Saint-Séverin, at the back right of a small square. This winding corridor topped with pointed roofs is not a cloister: built towards the end of the 15th century around the cemetery, it served to store the remains of bodies buried some time earlier in the mass grave, located where the square is now. It was customary for notable parishioners to be buried under the galleries, while the attics exposed to drafts were reserved for ordinary corpses.
At Saint-Séverin, the living quickly took the place of the dead: in the 17th century, some arcades were closed off with stained glass to allow for meetings of churchwardens, and above one gallery, housing was created for priests. Part of the galleries was demolished in 1840 to build a presbytery, with the remaining vaults restored in 1920 by architect Bévière.
Even more disturbing, on Rue de Vaugirard, beneath the Church of Saint-Joseph-des-Carmes: a crypt displays the remains of the religious massacred in September 1792, when the convent transformed into a prison held over 150 refractory priests. After a mock trial, 118 of them were killed in the gardens, next to the still-existing stairs. The bones, exhumed from a pit dug in the garden, are displayed in a very dramatic manner - a macabre detail, not a skull is intact. Upstairs, in an old cell, a wooden frame protects bloodstains left by the pikes.
In the heart of one of the rare islets of the Île de la Cité spared by Haussmann, Rue Chanoinesse evokes the cloister of Notre-Dame. Until the 18th century, canons lived there in a closed and guarded domain, dedicated to work and meditation - a closed ecclesiastical neighborhood in the evening, which maintained its own police.
Two canon lodgings remain, at numbers 22 and 24: they open onto the street through two large door frames leading to courtyards. In the second one, the façade of an authentic 18th-century wine merchant's shop is embedded, and the tradition continues as a restaurant under the sign "Vieux Paris" still serves the juice of the vine.
The real curiosity is at number 26. One enters a long courtyard, serving several buildings and lined with reused columns. It may be an old passage leading to Rue des Ursins, now a dead end. Look at the ground: long slabs cover it, and one can discern some traces of Gothic letters engraved. These are tombstones, coming from a religious establishment on the island. Quite practical, they allowed generations of Parisians to walk with dry feet, without too much concern for the respect owed to the deceased.
To complete the visit to the underground of the Cité, the small museum of Notre-Dame, at 10 Rue du Cloître-Notre-Dame, displays objects from the substructures of the first Merovingian cathedral, discovered in 1847 and then in 1965 - including a humble glass bowl base bearing a chrism, the oldest witness to the Christianization of Paris. It also showcases what was found in the cellars of a narrow alley that extended in front of the cathedral until the 19th century, such as a faience cup inscribed "buvé a la providence," probably used in the neighboring Hôtel-Dieu in the 17th century.
The most vibrant network remains that of the courtyards and passages, which allow one to traverse entire blocks without using the street. Here are a few routes to try:
Cour Damoye, 12, Place de la Bastille: the gate, closed at night, provides access to one of the most beautiful passages in the neighborhood. Antoine Pierre Damoye, a hardware merchant, bought a house and a garden here in 1778 where arquebusiers trained, then subdivided the lot - the opening of Rue Daval in 1780 offered him the ideal outlet. Shops and workshops topped with housing: it’s a bit of an ancestor of the covered passages of Paris. Look for the 1930s shop frieze, the 18th-century commercial facades made of simple beams on masonry bases, and the out-of-use metal freight elevator.Cour du Coq, 60, Rue Saint-Sabin: behind a beautiful green gate adorned with a rooster, a paved alleyway runs alongside an axial stream collecting rainwater. Its neighbors, Impasse des Primevères (No. 50) and Allée Verte (No. 58), recall the rural past of the area when Rue Saint-Sabin ran along the counterscarp of the fortifications.Passage du Cheval-Blanc, 2, Rue de la Roquette: you pass under a building from the late 18th century, then the passage bends and connects to 19-21, Rue du Faubourg-Saint-Antoine under the name Cité Parchappe, a succession of very different courtyards.Hôtel de Saint-Chaumond, 226, Rue Saint-Denis: a corridor crosses the building from 1734, leads to a second courtyard, then a final corridor pierced through a neighboring building opens onto 131, Boulevard de Sébastopol. The winding Paris of the 18th century is sometimes separated from Haussmannian breakthroughs only by a carriage door.Rue du Trésor, via 26, Rue Vieille-du-Temple: this dead-end born from the demolition of the Hôtel d'Effiat in 1882 - where a pickaxe uncovered a copper vase filled with gold coins - has a side door opening onto a passage to Rue des Écouffes.Rue des Innocents: the passage created under the building allows access to Rue de la Ferronnerie, where a ground marking indicates the location of Henri IV's carriage on May 14, 1610.
To this list, add two truly underground passages that are still accessible to all: the small corridor of the former seminary of the Thirty-Three, at 34, Rue de la Montagne-Sainte-Geneviève, whose door at the mezzanine connects with the other side of the college and Impasse des Boeufs, and the underground passage of the Jardin des Plantes, which starts from the gardens of the School of Botany, crosses Allée Cuvier, and opens at the heart of the alpine garden, buried three meters below the terraces.
What to remember, in short: the underground Paris is not only visited in groups and in overalls. It can be read in a sidewalk elevation, a staircase of fourteen steps, a wall too thick at the back of a courtyard, a low door at the end of a church. The above list is neither exhaustive nor definitive - boundaries shift, and the transformations of the city regularly remove some lovely specimens. So go out, walk aimlessly, note what you find, and do as the initiates of old: share your addresses like one shares a secret, remaining discreet on site.
Author Audrey on 15 February 2022
Travel and Tourism : Stay
Author Audrey on 06 March 2024
Travel and Tourism : Stay