According to Hollow Earth Theory, the Earth is a hollow planet with ancient entrances to the subterranean world scattered throughout it, including near both polar caps. Since ancient times, some have believed that there is an underground world inside our planet illuminated by a tiny sun, and it includes mountains, forests, and lakes.
Edmund Halley (1656 – 1742 AD), an English astronomer, geophysicist, mathematician, meteorologist, and physicist, may have been the first to develop a scientific hypothesis about a Hollow Earth. After a series of observations of the Earth's magnetic field, Halley concluded that the anomalies observed could only be explained if the Earth was composed of two spheres: an external solid one and an internal hollow one, each with its own magnetic axis.
The supposed evidence for the theory is that explorers have reported that air and water temperatures warm approaching the North Pole. People have also claimed that when Richard E. Byrd, the first man to fly over the poles, said he went “beyond the Pole” he was referring to having entered inner Earth.
Drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel The Goddess of Atvatabar (Public Domain)
Central Asian Buddhists believe the wonderful land under our feet is known as Agartha - a place where beings are more beautiful and much wiser than we are. It has a king that has the power to read the human soul and this ‘King of the World’ resides in Shambhala.