The Petite Ceinture or Little Belt, is a railway line in Paris. It was
started in 1852 but eventually lost favour to the Metro. It was a radial line intended, without much planning, to connect the various companies terminii and serve the various arondissements (city areas). It runs within what is now the peripherique road system and was complimented by an outer system, the Grande Ceinture. Paris, for all its size, is/was really a series of large villages clustered together.
The remaining parts of the PC are used for a small amount of freight traffic and for re-positioning of stock.