Schloss Wolfenbüttel is a castle in Wolfenbüttel, Lower Saxony, Germany. An extensive four-wing complex, it originated as a moated castle (Wasserburg). It is the second-largest surviving schloss in Lower Saxony and served as the main residence of the rulers of the Principality of Brunswick-Wolfenbüttel from 1432 to 1753. It now houses a gymnasium secondary school, the Federal Academy of Arts Education, and a museum with its historic rooms on display. Its immediate vicinity is home to several historically significant buildings including the Herzog August Bibliothek, the , the , and the Kleines Schloss.