A legend, Agartha, mentions there is a city on Earth. This is even referred to by some as the place of Gog and Magog or Gog and Magog.
Agartha is believed to be a city or kingdom on Earth. It contained alien beings with advanced civilizations. This belief has existed since ancient times, where people believed that the Earth was empty and filled with people of different races.
According to legend, the creatures in Agartha are more diverse but more harmonious than the life of humans who live on Earth. They also have perfect intelligence.
In science, there is a belief that seems to support the 'hollow earth' theory. Edmond Halley, an astronomer and geophysicist, in 1962 suggested that the Earth may have a depth of 800 km and consist of two spherical shells and a core. Between the plates is a vacuum, as the New York Post wrote.
This theory was supported by John Cleves Symmes Jr in the 19th century. Symmes believes that the north and south poles each have holes that can lead humans into Earth, as stated in the article reviewed at Atlas Obscura.
Even so, the teachings of science refute this theory. Geological researchers have conducted research and said that the Earth's surface to the core is 6,371 km. The Earth is not empty or hollow but has the core of the Earth. The Earth's core is believed to have a temperature of 6,000 degrees Celsius or 1,000 degrees hotter than the surface of the Sun.