PARIS.- The subterranean and unused spaces of the neighborhood of ’la Défense’ were opened to the public this past Saturday and Sunday as part of the ’ journées du patrimoine’ (days of the patrimony). During Sunday afternoon, in groups of twenty and without reservation, tourists were able to visit the gigantic and voluminous space known as  "underground cathedrals", situated under the pavement. The numerous tunnels, parking lots, expressways as well as the foundations of the buildings that have been built little by little at ’la Défense’ have left immense empty spaces that will never be filled. Some of these spaces, usually inaccessible for security reasons, had received visitors before the days of the patrimony but only by appointment. Visitors were able to visit the museum of ’la Défense’ where there are numerous drawings, projects and maquettes that since 1958 have guided the work-site of this business district, which counts with 2.3 million square-meters of offices occupied by 1,500 companies and where 150,000 people work daily.