Our collection on the speculations about the nature and inhabitants of our Hollow Earth (or, if you prefer, Cavern World), the many theories as to the form and nature of that hollowness — including the Concentric Spheres of Symmes, the Concave Earth of Koresh, etc. — and the authors of those theories.
This category has only the following subcategory.
Pages in category "Hollow Earth"
The following 21 pages are in this category, out of 21 total.
Media in category "Hollow Earth"
The following 3 files are in this category, out of 3 total.