http://www.librarising.com/hollow/hollowtable.html
(excerpt)
Our common conception is that Heaven is out there somewhere in the sky or in space, while Hell is underneath us, deep underground or at the planet's center. This would be accurate if the planet had a wholly solid interior, but it does not. Our planet is a hollow shell and at its center is a luminous sun or anomaly. It is engineered wisely and economically so that both the outer convex surface and the inner concave surface can be inhabited. This is possible when it is realized that the planet's gravity is in the middle of it's shell, and not its center. Polar openings connect the two surfaces in an unbroken fashion, and two suns, one outer and one inner, illuminate and warm both areas. Air and water flow also circulate unbroken from inner to outer and vice versa with the ice caps acting as a filtering system.
Not only are the inner and outer surfaces of our hollow planet inhabited, but the shell is as well. The Earth's shell, which varies from 400 to 800 miles in thickness, is made up of several layers or stratas, much like an apartment complex, wherein live many civilizations and Eco-systems. The shell is also honeycombed throughout with tunnels and cavern systems both natural and man-made. The caverns contain cities or communities, human and non-human alike, and are interlinked by high-speed shuttles or trains which run magnetically through the tunnels, much like our modern subway systems. Many of these transport systems reach both the outer and inner Earth surfaces, where trade and business is conducted, but only privileged or high-level functionaries have access to these ports.
All major outer Earth cities are linked to inner or Middle Earth sub-cities via secret tunnels, ports, shafts, elevators, and other passageways, where dignitaries and officials conduct commerce or exchange information.
Most of our technology comes from the inner earth. In the last few hundred years, inner earth societies have groomed the outer earth into its present modernized state. The goal is the eventual full integration of the inner and outer earth worlds into one world government or society. Whether this is for good or bad remains to be seen.
One of the great challenges confronting us is the safe integration of clean technologies in an otherwise fully organic world. Many believe that technology is a crutch or the work of the devil, and that the human organism has potentials that can outsurpass any technology.