Ancient myths from around the world describe numerous entrances to vast underground cavern-cities, within the bowels of the earth. Many occult organizations, esoteric authors, and secret societies concur with these legends of subterranean inhabitants, who are the remnants of antediluvian civilizations, which sought refuge in hollow caverns inside the earth.
A massive network of 12,000 year old underground tunnels discovered that stretch from Scotland to Turkey.
The prehistoric temples of Malta include many subterranean passageways, including ancient catacombs and chambers, with underground tunnels that have now been closed off to the public.
New Swabia (Neuschwabenland) is an area of Antarctica between 20°E and 10°W in Queen Maud Land. It was explored by the German Antarctic Expedition which discovered ice-free areas with warm fresh-water lakes and vegetation. In 1943, German Navy Grand Admiral Karl Dönitz stated: "The German submarine fleet is proud of having built for the Führer in another part of the world a Shangri-La, an impregnable fortress."