The site was to become the point of convergence of the RER, a network of new express underground lines which was completed 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), regarded as an eyesore at the foot of the historic church of Saint-Eustache.