Gate of Mystra
The headquarters and fortress of The Watchers, the Gate of Mystra was established many years ago by the Eternals, Sigmar and Rogal. Both saw the need to persevere and protect the Eye of Terror from those who might try to break its magic, or otherwise use it as a means to destroy the divine gate. Thus, the pair established the Watchers at the Gate of Mystra, and armed a group of orphans with the training, knowledge, magic, equipment and keep to do so.
The entire fleet of Obsidian Ships the Watchers maintains are done so from the Gate of Mystra. Thus it is established far out in the water. For many, sieging the Gate of Mystra is as difficult as sieging the Eye of Terror itself. It is warded in ancient magics, and protected by not only the watchers, but constructs built during the Age of Arcanum. It maintains a robust library, some say that could rival that of the Isle of Winds itself. Though its knowledge it mostly related to that of ancient evils from a time long before.