The Hollow Earth

[Image: 2012; see also their bit on Hollow Earth Cities].

"I declare that the earth is hollow," U.S. Army Captain John Cleves Symmes Jr. wrote in the early 1800s, "and habitable within; containing a number of solid concentric spheres, one within the other, and that it is open at the poles twelve or sixteen degrees. I pledge my life in support of this truth, and am ready to explore the hollow, if the world will support and aid me in the undertaking."
Somewhere along the line, Himalayan space ships, Nazi explorers, remnant Stone Age tribes, undersea caves, north-flowing Siberian rivers, and Edmund Halley all get involved... setting up BLDGBLOG's upcoming pitch for Indiana Jones 5...