10 things to know about the Paris metro

The Paris metro is the most heavily used stage set in France, and the least looked at. People go down the steps with their eyes on a phone and come back up having seen almost nothing. Which is a shame, because the network is full of strange decisions, records that keep changing hands, and the fossil traces of a century and a half of argument between the French state and the City of Paris.

Here are ten verifiable things about it, from a loading gauge that was deliberately made too small to a deepest-station record that changed hands in January 2025. If you then want to test what stuck, the full list of lines and stations is free to browse, and DailyMetro makes you guess one a day.

1. The first line was built in twenty months

Line 1 opened on 19 July 1900, running from Porte Maillot to Porte de Vincennes, in time for the World's Fair and for the Olympic events held in the Bois de Vincennes at the eastern edge of the city. According to the network history as Wikipedia records it, construction itself took twenty months, and the works were handed over to the City on 15 June 1900, a month before the public was let in.

Twenty months to cut across Paris from west to east, dug as an open trench down the middle of the main boulevards and backfilled, with shovels and tipper wagons. Recent extensions to the same network are measured in decades, most of it spent on procedure rather than digging.

2. The trains are narrow on purpose

Paris metro carriages feel cramped next to a suburban RER train, the separate regional rail network that runs through the city on its own, much larger tunnels. That is not penny-pinching, it is politics. The national government wanted a full-size network that main-line railway companies could run their own trains onto, which would have made Paris a through-station on a national system. The City of Paris wanted a network that was strictly municipal, and therefore strictly under its own control. The 1898 specification settled it in the City's favour, with a loading gauge of 2.40 m, too narrow for main-line rolling stock to pass.

So the width of a Paris metro train is a nineteenth-century turf war, frozen in concrete. More than a century later it is still the thing that stops the operator running anything it likes through those tunnels.

3. The 400-metre rule

The same 1898 specification required that no point in Paris should, in principle, be more than four hundred metres from a station. That rule, not chance, is why the network is so dense: 321 stations across 245.6 km of line, which works out at roughly 570 m between stops according to Wikipedia. It is one of the tightest station spacings in the world, and it is also why the Paris metro is slow. At an average commercial speed of 25.1 km/h, a train spends most of its life braking.

The flip side is a spread between individual stations that would be hard to believe if the numbers were not published. Here are the extremes as they appear in the annual ridership data the game uses.

Église d'Auteuil and Gare du Nord are on the same network, in the same city, and there is a factor of 275 between them. Very few systems anywhere allow themselves a gap that wide.

4. The worst accident was in 1903, and it changed everything

On 10 August 1903 a fire broke out on a motor car of line 2. Eighty-four people died, most of them at Couronnes and Ménilmontant, asphyxiated in the dark. It remains the worst accident in the history of the Paris metro.

The trains of the day were built of wood and wired with unreliable electrics. The disaster set off the first great wave of reform: wood progressively replaced by metal, emergency lighting on the platforms, illuminated signage, fire points in every station. Almost everything that makes a metro corridor recognisable as one today dates from that evening in August.

5. Rubber-tyred metro trains were invented in Paris, on line 11

Line 11, an unglamorous short line that climbs north-east towards Belleville, was the first metro line anywhere in the world to be fitted with rubber-tyred rolling stock. The first such train, the MP 55, was unveiled on 8 November 1956 and entered passenger service on 13 November.

Rubber was chosen for grip, line 11 being the steepest on the network, but the idea travelled a long way from Belleville. Montreal, Mexico City, Santiago and Lausanne all run on descendants of that Paris technology. Since June 2024 the line itself has run out to Rosny-Bois-Perrier, six stations further east than it used to.

6. Three lines already run with nobody driving

Line 14 has been fully automatic since it opened in 1998. Line 1 was converted in 2011 without ever closing, swapping one train at a time while passengers kept using it. Line 4 followed in 2023. Line 13, the one riders would most like fixed, is not promised until around 2035.

There is a reliable way to tell which kind of line you are standing on without knowing any of that: look for platform screen doors. If the doors sit in a wall of glass, the line is automatic, and you can go and stand at the very front of the train and watch the tunnel come at you, because there is no cab in the way.

7. Line 14 took the length record from line 13 in 2024

For a long time line 13 and its 24.3 km were the longest on the network, and its local nickname, the hell line, had something to do with that length. On 24 June 2024 line 14 was extended at both ends on the same day, north to Saint-Denis Pleyel and south to Orly airport, pushing it past 27 km. It is now the longest line on the Paris metro.

It is also the fastest, averaging about 40 km/h and touching 80 km/h where the alignment allows, against 21 km/h on line 4. On line 14 the run from Châtelet to Gare de Lyon is done in one go, with no stop in between, which on a network built around the 400-metre rule feels close to cheating.

8. The deepest station changed on 18 January 2025

For more than a century the answer was Abbesses, on line 12, whose platforms sit 36 m under the hill of Montmartre. Since Villejuif - Gustave Roussy opened on line 14 on 18 January 2025, the record stands at 36.7 m.

Seventy centimetres is a thin margin, but it counts, and Abbesses keeps a consolation title: deepest station inside Paris proper, meaning within the ring road that marks the city's administrative boundary. Villejuif is one of the suburban communes beyond it. The record will move again anyway, since the platforms of the future line 15 at Saint-Maur - Créteil are announced as considerably deeper.

9. Eighty-six Guimard entrances are protected

The cast-iron metro entrances in deep green, with lamp stalks that curl like plant stems, are the work of Hector Guimard and were designed for the network's opening. They are the most reproduced piece of Art Nouveau in the world and, for a lot of visitors, the single most recognisable object in Paris after the Eiffel Tower. There were once many more of them: according to Le Cercle Guimard and the counts reported in the heritage press, 86 are listed as historic monuments today.

Only two keep their full glass roof, the covered pavilions whose canopies look like dragonfly wings. Porte Dauphine is the only one still standing where it was built. Abbesses is not original to its site at all: it was taken down at Hôtel de Ville and rebuilt in Montmartre in 1974, to make way for an underground car park.

10. There was a 9 km/h moving walkway at Montparnasse

Between 2002 and 2011 the interchange corridor at Montparnasse - Bienvenüe housed a 185 m high-speed moving walkway, designed for 12 km/h and finally certified at 9 km/h. You had to grab a handrail, accelerate as you stepped on and decelerate as you stepped off. It was a genuine skill to acquire, in a corridor where everybody is already running for a train.

Falls and breakdowns finished the experiment off. The operator announced its removal in May 2009 and replaced it with an ordinary walkway in March 2011. Montparnasse - Bienvenüe is still one of the longest walks between platforms on the network: its four lines (4, 6, 12, 13) are spread across what were originally two separate stations, later joined by that corridor.

If you would rather play than read, there is a comparison of every Paris metro game worth your time, including the ones I did not make. And the Paris network explorer has a page for each of the 321 stations, with opening year, ridership and interchanges.