Floating above the center of the lightly wooded Wollvern Park is the Tower of the Twelve, a magicians’ college where the dragonmarked houses send their best and brightest. This thirteen floor tower (with one empty floor to memorialize the lost Mark of Death) is full of classrooms, libraries, and laboratories devoted to arcane research. The Tower of the Twelve is the primary rival to the Arcane Congress, but only those affiliated with a dragonmarked house can enter and study within.
Losses during the Last War and the political ramifications resulting from its aid to Karrnath diminished the Twelve’s standing in the Five Nations, allowing the Arcane Congress to eclipse it. The Twelve struggles to rebuild, but it’s unclear whether the organization can recover fully.
Source: Five Nations