What is the best metro system in the world?

Cheap, fast and enormous for the size of the city it serves.

Carries more passengers a year than almost anywhere, on trains that arrive every two minutes.

Bold 1970s colour schemes and a network that empties a stadium in minutes.

The only major system running 24 hours a day, every day, across 472 stations.

Spotless, fully air-conditioned and policed by fines that people actually obey.

The world's first underground railway, opened in 1863, and still the shape of every network built since.

Dense enough that almost nowhere in the city is more than 500 metres from a station, wrapped in Guimard's art nouveau entrances.

Chandeliers, mosaics and marble halls built as palaces for the people.

Built almost entirely since 1993 and now the longest network on earth.

Small, immaculate and consistently near the top of European transport surveys.

Quiet carriages, orderly queues and a reputation for cleanliness that rivals Tokyo's.

Runs on trust rather than barriers, and all night at weekends.

Blasted rock caverns painted into what is often called the world's longest art gallery.

One of the cheapest fares in the world, with a pictogram for every station.