Located next to the Tower Colony, the ruins of the Tower of Magi, is the Surface Portal. Engineered to send large caravans of merchants and merchandise from Avernum to the Empire, and vice versa, it is an extremely large portal. It is the only permanently-maintained portal between the caves and the surface, and the only portal period that is large enough to facilitate large-scale trade between the nations. It is also the largest piece of magical machinery in Avernum, and among the largest on Ermarian. The portal can be configured to travel between its location in Avernum to several large centers of trade on the surface.