The Lost City is a very ancient subterranean city inhabited by the hostile species known as Sleestaks and their god, and protected by the ferocious female Allosaurus dinosuar named Big Alice. This city is a recurring location in the 1974 TV series Land of the Lost, as well as its 2009 film adaptation of the same name.
A long time ago, the Altrusians have built the Lost City into the base of a mountain within a region of the Land of the Lost. Now, it is their descendants the Sleestaks who live in it, although the city is partly abandoned. The city consists mostly of an underground tunnel complex and contains several important places, such as the Library of Skulls, the fog-filled pit called the "Hole of No Return" within which lives the Sleestak God, and the Nursery where the eggs are kept.
On the outside, the Lost City consists of a huge plaza with an arched entrance, crumbling rectangular pillars, and three tunnel entrances set into a mountainside. Big Alice spends most of his time on the plaza and protects the city from trespassers.
The Sleestaks do not tolerate intruders and attack anyone who penetrates into the Lost City, especially the Marshalls.