Drowned Wizard's Tower
From West Of Vipers Gate
Former Library and place of knowledge of the Wizard's Guild, a powerful wizard owned the place for centuries, and the guild stored knowledge, spells, demons, and other creatures in its walls, until, three centuries ago, the last wizard sunk it beneath the waves to hoard its knowledge as her own.
The tower was being used as the home of the lich Eldon of Milthorn. However, Morgan used Mar's Glare to sink the tower beneath the waves totally.