Two entries with the name Merlin’s Tower.
Merlin’s Tower
An enchanted tower between the White Castle and the town of Gasan.
It was prophesied that only Lancelot would end the enchantments.
Source
Vulgate Lancelot | 1215-1230
Merlin’s Tower
A tower on the Turning Isle (Turnance) once inhabited by Merlin.
Source
Le Livre d’Artus | Early 13th century