Paris: 6 underground places to visit (that you've probably never heard of)

Without ever having been down there, everyone knows about the catacombs of Paris. They've even become a must-see for tourists. But what we often don't know is that they are actually former quarries and that less than 1% of their surface is accessible to the public, which gives you an idea of the vast extent of these underground galleries: 350 kilometres! And there are plenty of them as far away as Meudon.

A film by P. Tchernia was devoted to them in 1974, "Les Gaspards", recounting the adventures of a group of misfits who actually lived there. It was a way of introducing us to the existence of these galleries, which were totally unsuspected at the time. These include the Salle Z in Val-de-Grace, once the scene of clandestine parties, a secret cinema beneath the Palais de Chaillot and "La Plage", a former brasserie hidden in the underground passages of the 14th arrondissement. Those in the know will know that there are open-air entrances to these forbidden zones, often sealed but sometimes open.

Underground there are... the sewers, of course! But did you know that you could visit them? Paris City Council organises guided tours in the company of a sewer worker. They last about 1 hour and are organised in groups. This is one of the rare opportunities you'll have to go deep into the capital's innermost depths, to understand how it works and what the sewage workers do. You can also learn the secrets: engineering, the scourge of fatbergs (Dantesque agglomerations of grease) and the animals that live here. With its 2,600-kilometre network, it's easy to understand the complexity of this gigantic system working to treat our water and waste.

For the less adventurous, the Musée des Egouts de Paris awaits you at Esplanade Habib Bourguiba, Pont de l'Alma, in the 7th arrondissement.

This famous Parisian canal runs from the Seine, near the Arsenal marina, to the Place de la Bataille de Stalingrad. It crosses the 11th arrondissement, from Place de la Bastille to Place de la République, entirely underground. This access is forbidden to pedestrians and is therefore fenced off, but you can get round this obstacle by planning a discovery trip on the water. There is a canal cruise that takes in this section of the canal. Don't forget to pack a jumper, as it's a bit chilly.

Under the low arch of the tunnel, you'll recognise nothing less than the starring role played by Ethan Hunt, alias Tom Cruise, in his Mission Impossible: Fallout! partly filmed in Paris.

The disused Porte des Lilas metro station is a vestige of the old Paris metro. Opened in 1921 on line 11 to serve the Porte des Lilas district, the station had to close in 1939 because of the war. It became a storage area for works of art from the Louvre. Or, in the jargon of ferrivopaths, a "dead platform".

It should not, of course, be confused with the current Porte des Lilas station, which is very much in operation. In fact, it was the Porte des Lilas station on the shuttle and Fêtes lines that was renamed Porte-des-Lilas-Cinéma. It only reopened for 4 years in the 1950s, and is now used as a film location for scenes set in the metro: JP. Jeunet filmed the scenes in Le Fabuleux Destin d'Amélie Poulain that were supposed to take place at Abbesses station. In 2022, a scene from John Wick - Chapter 4 was filmed there.

There is also the Haxo station, which is next door to Abbesses station, but unlike Abbesses station, there is no above-ground entrance directly connected to it.

Both stations are open to the public on Heritage Days. Please also note that it is possible to visit some of these 13 ghost stations of the Paris metro on guided tours of the rail network. Find out more at the end of this article.

Nestling beneath the stage of the opera house's main auditorium, this artificial body of water was designed by Charles Garnier, the opera house's architect, as a purely utilitarian structure. Its function was twofold, as it served as an outlet for the water that naturally seeped into the basement walls, and also as a reservoir that could be useful in the event of a fire. In the 19th century, there was no fire hydrant that could be connected to the fire engine!

Find out if this tour will be open to the public on the next Heritage Days.

You can already get an idea here.

Everyone knows about the metro, but what you may not have realised is that you can visit its network! Thanks to the ADEMAS association, you can learn a lot about the underground world that has become our capital's rail network. Imagine, for example, the ingenuity and hard work it took in the 19th century to go under the Seine, given the huge volume of water it represents? And did you know that underground passages had to be built on stilts to cross or bypass the underground quarries?

You're in for a real treat on this tour, which will tell you more about our beautiful capital than you can imagine. Also on the menu: closed stations and the beginnings of aborted routes.