Les Halles was the central Market in Paris. In 1183, King Philippe II Auguste enlarged the marketplace in Paris and built a shelter for the merchants, who came from all over to sell their wares. Known as Les Halles, for almost 700 years the masssive glass and iron building was the "stomach of Paris".
Unable to compete in the new market economy and in need of massive repairs, the colorful ambience once associated with the bustling area of merchant stalls disappeared in 1971, when Les Halles was dismantled.
The site was to become the point of convergence of the RER, a network of new express underground lines which had been inaugurated in the 1960s. Three lines leading out of the city to the south, east and west were to be extended and connected in a new underground station. For several years, the site of the markets was an enormous open pit, nicknamed "le trou des Halles" (trou = hole), and a considerable eyesore at the foot of the historic church of Saint-Eustache.
Construction was completed in 1977 on Chatelet-Les-Halles, Paris's new subway hub. The Forum des Halles, a partially underground multiple story commercial and shopping center, opened in 1979.