Burg Oebisfelde, one of the oldest preserved swamp castles in Europe, was likely built in the 10th century and served to protect the Aller crossing. The medieval complex, with its impressive keep and well-preserved inner courtyard, is now used as a museum, library, and tourist information center. Regular markets, concerts, and the popular Altstadtfest in June make the castle the cultural center of Oebisfelde-Weferlingen. Visitors can climb the keep and immerse themselves in the history of the region.Wikipedia