As theories go, the idea that the Earth is hollow does not garner a lot of respect. For most people, the hollow Earth is probably a close second to the "Earth is flat" theory on that big list of "crackpot" ideas. Nevertheless, as long as there have been people able to sit around a campfire, tales of a mysterious inner world have been part of mankind's heritage.
Unlike the flat Earth, the hollow Earth has not disappeared into that great dustbin of quaint and old-fashioned myths of our ancestors. No longer does anyone have stories to tell of angels taking them up on-high to view the flat Earth, but even into this modern age of spaceflight and personal computers, there are still claims of personal encounters with the lands and people of the inner world.
Part of the hollow Earth mystique is that many ancient civilizations have similar creation legends that involve mankind birthing from the subterranean realm. Some of these myths even seem to suggest that people first came to the surface world via a great opening located somewhere in the northern polar regions.
My picture is made upon old illustrations in Marshall B. Gardner's book "A Journey to the Earth's Interior" from 1920. Diagram showing the earth as a hollow sphere with its polar openings and central sun. The letters at top and bottom of diagram indicate the various steps of an imaginary journey through the planet's interior. At the point marked "D" we catch our first glimpse of the corona of the central sun; at the point marked "E" we can see the central sun in its entirety.