GREAT UNDERGROUND SAVANNAH

Dimwit Flathead's mania for including every conceivable ecosystem under his roof did not exclude a savannah. This flat grassland entirely beneath Flatheadia, ended at the Great Underground Woods to the northeast, and at the Great Underground Desert to the west. These plains were home to grazing herds of unicorns, as well as one of the Four Fantastic Flies of Famathria.

SOURCE(S): Zork Zero