Metro, the Paris

   First opened in 1900, the Paris Metro (or Métropolitain) is the city's subway system or underground railway system. Most of the network within central Paris is underground, though there are some aerial sections, notably on routes 2 and 6. It is linked with the city's suburban rapid transit system, the RER. The Paris Metro is Europe's second most-used urban subway system after the Moscow underground. Most routes use standard gauge steel rail tracks, though five of the routes operate with rubber-tyred rolling stock, running on concrete tracks. These are considerably quieter than the traditional trains used on other routes. The most recent route, line 14, opened in 1998 and known as the "Météor", uses driverless trains.