Geofront

A geofront is a science fiction concept, referring to a large, excavated subterranean space typically used for urban expansion.

The concept appears in numerous media:

• anime: Patlabor (ep 19), Neon Genesis Evangelion, Ghost in the Shell, CB Chara Nagai Go World;
• video game: Ace Combat 3: Electrosphere;
• in other franchises: Doctor Who, The Matrix;
• literature: Isaac Asimov's novel The Caves of Steel. A parent concept of a subterranean world is also found in Jules Verne's novel A Journey to the Center of the Earth.