Oost Castle is a manor house in Oost-Maarland, a village in Eijsden, Limburg, the Netherlands. Located along the Meuse, it can be traced to an 11th-century motte-and-bailey residential tower that was expanded several times between 1548 and 1800. After falling into dilapidation, it was renovated in 1848 but had fallen into dilapidation again by the beginning of World War II.