Antartica

Coordinates = -66.553217,99.838294

Take a Look!

https://www.google.com/maps/search/-66.553217,99.838294/@-66.5529182,99.8385944,268m/data=!3m1!1e3

An advanced civilization lives there.

As early as 1943 the boastful German Navy Grand Admiral Karl Dönitz said:

The German submarine fleet is proud of having built for the Führer in another part of the world a Shangri-La on land, an impregnable fortress.

Yet another one of Himmler's peculiar pet projects in his quest to create the perfect Aryan race was allegedly sending 10,000 of the purest Ukrainian woman of German-Slavic descent and 2,500 SS bluebloods from the Russian front to Antarctica in order to breed the future super race in their polar base and alleged city New Berlin being built.

 Thousands of German scientists were listed as dead or unaccounted for, 250,000 German citizens whose whereabouts were unknown, and over 100 submarines remained unaccounted for. Persistent rumors circulated that even Adolf Hitler and Eva Braun had fled safely to his Antarctic underground base.