Death Zone
The Death Zone was a place well known to the first five Doctors. These Doctors were brought to the Death Zone and were forced to fight all the beings that resided there (such as the Cybermen, Daleks and Yetis)
The Death Zone was comprised of various different terrains which allowed different species to survive. There were mountains, marshes and one road (which the Third Doctor used with Bessie). The fog was thick so one couldn't see where one was going and it was difficult to see the red thunderbolts that fell from the sky. The Doctors were sent to the Death Zone and had to reach the tower(to find a way to go back home); all Five Doctors succeeded in this task. beacuase of rassilon who sent them home. (DW: The Five Doctors)