Schloss Schwetzingen, or Schwetzingen Castle is a palace in the German state (Bundesland) of Baden-Württemberg. Schwetzingen was the summer residence of the Electors Palatine Karl III Philip and Charles Theodore. It is situated in Schwetzingen, roughly equidistant from the electors' seats at Heidelberg and Mannheim, and is most notable for its spacious and ornate gardens. Other than these exceptionally well preserved gardens and the castle proper, the compound also features the Schlosstheater Schwetzingen, the principal venue for the annual Schwetzingen Festival.The mosque in the gardens complex is the earliest mosque-style building in Germany. It was built in 1779-1791 by a French architect for the Prince Elector of the Palatinate. Built at a time when the "Turkish" style was fashionable in Germany, it was never intended for prayer but later served religious purposes at various times..