The Senne River had long been subject to torrential flooding, notably in August 1850, and had also become increasingly polluted. Following a cholera epidemic that killed an estimated 3,467 residents in May 1866, the authorities, led by Burgomaster Jules Anspach, decided to cover over the river both to make the center of Brussels a healthier place and to demolish derelict structures in the interest of urban renewal. As duke of Brabant, the future king Leopold II had been greatly impressed by the wide boulevards laid out in Paris under Georges-Eugène, Baron Haussmann (1809-1891), and he readily endorsed the scheme, on which work was begun in 1867. Architect Léon Suys managed that portion of the project involving vaulting over of the river, which was canalized and the waters channeled to Humbeek. The work was completed in 1874, when, on 15 November, Leopold opened the sluices amid great festivities.
The river runs underground just south of the Gare du Midi to reemerge at the pont van Praet in Laeken, where it follows the Wille-broeck Canal in the direction of Mechelen.
Jean-Baptiste Mosnier, a Parisian building contractor, was commissioned to construct the boulevards, and French contractors built many of the buildings along the routes. Roadwork was carried out by the Belgian Public Works Company, which employed local laborers. The project entailed cost overruns and a lawsuit involving the company and the city. The latter eventually completed the work itself.
Vaulting transformed the city center as many winding, narrow streets dating from the Middle Ages were eliminated with the installation of the boulevards Maurice Lemmonier, Anspach, Adolphe Max, and Émile Jacqmain and the opening of the squares Fontainas, Bourse, and de Brouckère. Construction launched a new development in architecture with the French influence much in evidence in the façades of the 62 buildings built before Mosnier went bankrupt in 1878, many of which were constructed of stone imported from France in place of brick, the traditional building material of Brussels.
Stretches of the river upstream and downstream of Brussels were vaulted over in the 1950s.
Historical Dictionary of Brussels. Paul F. State.