In the heart of the city Schloss Mannheim dominates as a prominent Baroque building; since 1967 it has primarily served as the seat of the University of Mannheim and shapes the urban layout of the Mannheimer Quadrate.
The building stands at the highest point of the historic part of the city and was erected on the remains of older fortress and palace complexes that were destroyed and rebuilt several times from the early 17th century onward. The foundation stone for the Baroque three-winged structure was laid in 1720 in the presence of the court; several construction phases followed, accompanied by recurring financing problems and phased alterations. Originally planned figurative façade decorations and a continuous balustrade crowning were only partially executed for cost reasons.
Over the course of the 18th century the representative central block with a generous staircase, the Rittersaal, a dedicated palace chapel with crypt and an extensive east wing housing collections, a treasury, the court library and archives were created. Significant Rococo and Baroque fittings, including ceiling paintings and relief work, characterized the main floor; much of the pictorial decoration was produced by contemporary Baroque painters and sculptors. Around 1760 the building was largely regarded as complete.
The complex of elongated wings, pavilions and a palace chapel makes use of Buntsandstein and mineral glazes; its length of almost 450 metres and a built-up area of about six hectares make it one of the largest Baroque palaces in Europe, ranking after Versailles. A design detail was the deliberate number of windows, intended to symbolize the court’s rank. The orientation of the ensemble continues to determine the rectangular block structure of the inner city, the so-called Mannheimer Quadrate.
After alternating use as a residence, a widow’s residence and an administrative building, the palace was almost destroyed in the Second World War. The ruins were secured in the postwar period and largely rebuilt; crucial to its survival was the gradual restoration from the late 1940s, with the main reconstructions taking place between 1957 and 1964. In the 1960s central rooms were reconstructed, with ceiling paintings reworked using historical photographs.
Today the wings of the complex house university facilities, the university library and parts of the judicial administration. In the reconstructed representative rooms of the central block a palace museum has been established, displaying carpets, furniture and works of art from Kurpfalz and Baden in historically oriented room settings.
As part of restorations carried out around 2005–2007, façades, mansard roofs and the square areas were reconstructed; since then the discussion about restoring further Baroque elements and the historical guardhouses has continued.