The Sprengel Museum in Hanover houses one of the most significant collections of modern art in Germany. It is located in a building designed by Peter and Ursula Trint (of Cologne) and Dieter Quast (of Heidelberg), adjacent to the Maschsee. The museum opened in 1979 and the building was extended in 1992. Bernhard Sprengel donated his extensive collection of modern art to the city of Hanover in 1969, as well as financially supporting the construction of the museum. The city of Hanover and the state of Lower Saxony agreed to jointly operate the museum. In addition to the works donated by Sprengel, the museum also houses 20th century artworks owned by Lower Saxony and Hanover.