Nightbringer | The Arthurian Online Encyclopedia

Lancelot’s Tower

Chrétien describes an island in the middle of the large, broad arm of the sea that lay beside Gore. Upon this island Meliagrant had a tower built for the special purpose of imprisoning Lancelot: The stone for this tower had to be ferried over the water, and its construction took almost fifty-seven days.

Later on, however, in the part added by Godefroi de Leigni, the tower seems to be not on an island, but standing lonely on the shore beside the arm of the sea.

See also
King Bademagu’s Daughter | The Legend of King Arthur