Hollow Earth: the long and curious history of imagining strange lands, fantastical creatures, advanced civilizations, and marvelous machines below the earth's surface

by David Standish

Not the most scintillating writing, but effective enough and straightforward. Entertaining and informative, if you like reading about kooks and cranks. The book covers many oddball theories about our third rock from the sun, from literature to pseudoscience, occult mysticism to early twentieth century health food cults, religious movements and utopian societies: unknown civilizations (and/or dinosaurs) living in caverns deep inside the earth, attempts to prove the earth is flat, Hitler's alleged belief that we are living on the interior surface of a sphere, to name a few. Some of these ideas are sort of understandable, given the state of scientific knowledge when they were formulated, some are wild speculation and obvious fabrication regardless of origin. The author doesn't mock any of these theories (that would be me), he tries to show their cultural context and connection the zeitgeist. A-plus for the illustrations, too.