The Paris Métro is a rapid transit system in the Paris metropolitan area, France. A symbol of the city, it is known for its density within the city limits, uniform architecture and unique entrances influenced by Art Nouveau. It is mostly underground and 214 kilometres (133 mi) long. It has 303 stations, of which 62 have transfers between lines. There are 16 lines, numbered 1 to 14 with two lines, 3bis and 7bis, which are named because they started out as branches of lines 3 and 7; later they officially became separate lines; the Metro is still numbered as if these lines were absent. Lines are identified on maps by number and colour, and direction of travel is indicated by the terminus.