The architects, Peter and Ursula Trint (Cologne), together with Dieter Quast (Heidelberg), designed the main building of the museum, which was opened in 1979, as well as the extension thereof, which was completed in 1992, guided by the concept of dialogue between 'openness and closure'. The combination of 'public space' and 'space emitting the aura of art', allows the museum to be a place which is conducive to communication due to its 'open' character- it is an inviting structure.It all started with a very generous gift: in 1969, Dr. Bernhard Sprengel gave his extensive collection of modern art to the city of Hanover and also offered a considerable sum towards the building of an appropriate museum. The city and the provincial government of Lower Saxony decided to share responsibility for the construction and running of the museum. The Sprengel Museum Hannover combines the Sprengel Collection of 20th century art with the city and provincial government collections in one unique location. The combination of these collections gives the Sprengel Museum Hannover the status of one of the most significant centres of modern art in the country. The exhibits are organised thematically and not, as is sometimes the case, chronologically or alphabetically. Some of the movements on display include German Expressionism, French Cubism, post-war Abstract Art, Minimal Art, Informalism, Nouveau Réalisme, Conceptual Art and Post-Minimalism. Important recent additions have also been made to the collection to include photography and new media. The organisation of the exhibitions is one of the exceptional qualities of the museum. Special mention must be made of the spaces devoted to individuals such as Pablo Picasso, Ferdinand Léger, Max Ernst, Emil Nolde, Paul Klee and Max Beckmann. The unique collection of works by Kurt Schwitters, and the one of a kind 'Cabinet of Abstraction' by El Lissitsky are the highlights of period from 1920 until the war. Other elements of the collection include notable groups of artworks by Hans Arp, Lyonel Feininger, Ernst Wilhelm Nay, Emil Schumacher, Keith Sonnier and James Turrell, in which many of this century's most significant pieces can be viewed. Another category which forms a bulk of the collection is devoted to classical Modern Art, composed primarily of paintings and sculptures from the first half of the century. Important artists' groups, such as 'Die Brücke' and 'Der Blaue Reiter', movements (Surrealism, Cubism) and personalities (Dix, Boccioni) are represented by a gamut of individual pieces. One of most individual characteristics of the museum are the rooms composed by an artist as an installation. The reconstructed 'Cabinet of Abstraction' by El Lissitzky and the recreation of Kurt Schwitters' Merz room provide two exceptional but very different types of spatial composition for the viewer. The new room featuring four light installations by James Turrell continues this tradition in a contemporary vein.