An enormous tower that has been around for many, many millenniums. It contains volumes of dangerous books, many dangerous magical artifacts, and a cloister of trials that help improve a magician's power and rank.
The tower was originally used to train those born with magic in their veins, though that all ended about 2000 years ago when a great barrier was erected due to a war with the Tower of Mages, stopping all from going in, and all that was trapped inside were trapped for eternity. It wasn't until recent years where the great barrier was shattered and access to the tower was possible again. The wizards whom were stuck in a time stasis now seek new blood to train as future Grand Wizards.
