First appears in: The Twin Fury
The Suldusk Building is an academic structure on the campus of Ilyrion University on Valaralda, dating back one hundred thousand years to the time before the Great Awakening. It is one of "three more big brick structures" that sit past the "vast central lawn" of the campus quad.
The building is the location where the junior astronomy professor Aten teaches his sparsely attended classes. It is inside a classroom in the Suldusk Building that Aten's students first inform him of the "unexplained phenomenon in the sky"—a mysterious orange ball of light that turns out to be the arrival of the Twins and the Xyclami device from Starmist Prime.