Suspended above the desert of the Realm, the Tower has no visible markings or architecture: it is just a pendulum of stone, several hundred feet high. At its base is the Well of Making. Beyond that, in the abyss below is, as Crow reported, quite literally, nothing. There is no means of access to the Tower from the desert - finding a means across was April's Trial of Matter. She used water from the Well of Making on the Nothing below, and a bridge was created.