Tower

Within the Twelfth Doctor's confession dial, a castle had a tower which held a wall of azbantium, which took the Doctor four and a half billion years to break out. (TV: Heaven Sent/Hell Bent)
The Tomb of Rassilon was contained within a tower inside the Death Zone on Gallifrey. The journey within the tower was laid with various traps and puzzles as part of the Game of Rassilon. (TV: The Five Doctors)
In Teen Titans, the Teen Titans lived in a tower shaped like a "T". (PROSE: Father Time)