Chemin de fer de Petite Ceinture

The Chemin de fer de Petite Ceinture (de Paris) (French for "little belt railway"), as it was called in its later years, was a circular railway built to provide rail correspondence between Paris's main railway stations and a means to supply the city's then fortifications. Built in stages from 1851, its first years was as two distinct 'Ceinture Syndicate' freight and 'Paris-Auteuil' passenger lines that formed an arc that surrounded the northern two thirds of Paris, but when its third Rive Gauche section of rail had been built in 1867, it had become relatively homogenous freight-passenger-service ring of rail around the city. Serving almost as Paris' first metro line, it gradually shed its freight function as it rose in popularity to its 1900 Universal Exposition peak, but the Metro appearing that year would mark the onset of its decline.

Mostly abandoned since its last year of service in 1934, but still largely intact, its future is still the source of much debate as of 2017. Many would like to preserve the remaining stations as part of France's national heritage, while others would like to see its former path transformed into parks and communal gardens, and yet others, rail enthusiasts for the most part, would like to see, in some form, the track and stations remaining become a functioning line once again.

France's first steam-locomotive-driven passenger rail service was its 1837 Paris-Saint-Germain railroad that ran to an 'embarcadère' ancestor of today's Gare St-Lazare station. In the years following, new railways appeared in many regions across the country, but in all, its early 19th-century rail technology expansion was far behind that of its western European rivals. The Louis-Philippe government-monarchy planned to close this gap with their 1842 "Legrand Star", a map of pre-programmed railway concessions that made Paris the centre of a spiderweb network of lines reaching to all regions and borders of France. By the end of the decade, France's rail was ruled by five distinct railroad companies, each with their own exclusive monopoly over their respective regions of France.

Paris was only half its present size in the years of the Ceinture's creation: its limits then were the city's 1784 Fermiers-Généraux tax wall that followed almost exactly today's Métro lines 6 and 2). From 1841, Paris doted itself with a ring of defences a few kilometres outside these: completed in 1845, the Thiers wall fortifications enclosed land that was mostly countryside, save for a few 'faubourgs' extending for a distance along the roadways from its city gates.

...
Wikipedia