Hollow Earth

historical concept proposing that the planet Earth is entirely hollow or contains a substantial interior space

alt=Refer to caption|upright=1.2|thumb|An illustration of Agartha within the hollow Earth, from Walter Siegmeister's 1960 book Agharta Agartha (variously spelled as Agharta, Aghartta, Agharti, among many other spellings) is a legendary kingdom said to be on the inner surface of the Earth. Though the story has many different versions, Agartha is usually said to be in Central Asia and led by a powerful figure sometimes called the King of the World, who secretly influences the surface. Later versions connect it to the belief in a hollow Earth. The idea of Agartha has been a popular subject in eso

speculation that Moon is hollow

Urban legend