Bodrum (bōˈdrum) [key], town (1990 pop. 20,931), Muğla prov., SW Turkey, on the Bodrum peninsula on the Aegean Sea coast. It was built on the ruins of the ancient city of Halicarnassus during the early 15th cent. A popular tourist resort, the town's notable landmark is a 15th cent. castle. It is also a center for underwater archaeology in the Mediterranean.