Covering of the Senne

The covering of the Senne (French: Voûtement de la Senne; Dutch: Overwelving van de Zenne) was the covering and later diverting of the main river of Brussels, Belgium, and the construction of public buildings and major boulevards in its place. Carried out between 1867 and 1871, it is one of the defining events in the history of Brussels.

The Senne/Zenne (French/Dutch) was historically the main waterway of Brussels, but it became more polluted and less navigable as the city grew. By the second half of the 19th century, it had become a serious health hazard and was filled with garbage and decaying organic matter. It was heavily polluted, and it flooded frequently, inundating the lower town and the working class neighbourhoods that surrounded it.

Numerous proposals were made to remedy this problem, and in 1865, the City of Brussels' mayor, Jules Anspach, selected a design by the architect Léon Suys to cover the river and build a series of grand central boulevards and public buildings. The project faced fierce opposition and controversy, mostly due to its cost and the need for expropriation and demolition of working-class neighbourhoods. The construction was contracted to a British company, but control was returned to the government following an embezzlement scandal. This delayed the project, but it was still completed in 1871. Its completion allowed the construction of the modern buildings and boulevards that are central to downtown Brussels today.

In the 1930s, plans were made to cover the Senne along its entire course within the greater Brussels area, which had grown significantly since the 19th-century covering. By 1955, the course of the Senne was diverted to the downtown's peripheral boulevards. In 1976, the disused tunnels were converted into the North–South Axis of Brussels' underground tram system, the premetro. Actual purification of the waste water from the Brussels-Capital Region was not completed until March 2007, when two treatment stations were built, thus finally cleansing the Senne after centuries of problems.