The Tower - Ba'Sal

Located in the bustling city of Penumbra, The Tower is a mile-high structure made of polished obsidian. Though no windows or doors are visible from the outside, those inside need merely think of the outside a window will form for them ... allowing them to see out but no one to see in. The only public door into The Tower requires a magical phrase to enter. Depending on the phrase, The Tower will grant access to only some of its rooms, delivering the visitor to that place immediately.
It is rumoured that the Vespertaal of The Tower, in an effort to escape the attacking God Tower, plans to wall their Tower and the surrounding countryside in another dimension, sealing themselves from the world.