La Petite Ceinture (little belt) was built between the 1850s and 1870s to connect the main railway stations of Paris. Designed to carry passengers and freight, it soon become the first metro in Paris, but from 1900 onwards, with the first modern metro lines built, passenger numbers declined and in 1934 the line was closed to passengers. By the early 1990s freight traffic too had also largely ceased. Apart from a few sections that have been transformed into public parks, most remain a landscape in limbo – a secret (or not so secret) route around the city.