Graventoren, located in Rupelmonde near Kruibeke, Belgium, is the sole surviving tower of a grand 12th-century moated castle that once belonged to the Counts of Flanders. Originally featuring seventeen towers, the castle was expanded by Margaret of Flanders in the 13th century and served as a military fortress until 1748. Today, it functions as a museum dedicated to the celebrated cartographer Mercator, who was imprisoned here in 1544. An observation platform offers panoramic views of Rupelmonde and the surrounding region.
