Agartha is a legendary city that is said to reside in the earth's core. It is related to the belief in a hollow earth and is a popular subject in esotericism. Agartha is frequently associated or confused with Shambhala (humansarefree, 2013)
Real or not, judge yourself: Perhaps the most intriguing photo purporting to show the North Polar opening into the Hollow Earth, this one taken by the American space station Skylab in 1974 - but not released to public view until 2006, and then only because it was leaked to the Internet. This one is so crystal clear it even seems to show sunlight from the so-called ‘central sun’ emanating from within. Once again, from NASA: ‘No comment.’ “Hoax or Smoking Gun? 1880-2008."