In 'The Wheel of Time', the island city that serves as the seat of the White Tower is Tar Valon.
Tar Valon is built on an island in the River Erinin and occupies a strategically central position between several major nations. Its location makes it a vital crossroads for trade, travel, and diplomacy. The city is surrounded by extensive walls and is connected to the mainland by six bridges, each leading toward a different settlement.
At the heart of Tar Valon stands the White Tower, the headquarters of the Aes Sedai. The Tower houses the Amyrlin Seat, the supreme leader of the Aes Sedai, as well as novices, Accepted, sisters of the Ajahs, servants, and soldiers. The seven Ajahs specialize in different duties, including healing, diplomacy, scholarship, espionage, and warfare.
Tar Valon is often confused with other important cities in the series. Caemlyn is the capital of Andor, Cairhien is the capital of the nation of the same name, and Tear is a powerful city-state in the south. The White Tower is not a separate city: it is the dominant institution and landmark within Tar Valon.