The Søndermarken Cisterns were constructed (originally as uncovered reservoirs) between 1856 and 1859 to provide the city of Copenhagen with clean water. As well as serve the growing population, clean water was also needed to reduce the risk of infectious diseases such as cholera. By 1889, as a result of growing pollution, the reservoirs were enclosed with concrete caps. The three cisterns formed could hold 16,000 cubic metres of water. They became largely redundant in the 1930s but were not fully decommissioned until 1981. Today the splendid chambers can be visited as part of the Frederiksberg Museums and exhibitions are held where renowned artists and architects design installations specifically for this hidden space.