UFO conspiracy theorists claim to have found evidence in Google Earth satellite imagery of an ancient city buried in Antarctica ice. According to conspiracy theorists, what looks clearly like an artificially constructed fort-like structure was spotted emerging from beneath Antarctica ice in satellite imagery.

The giant structure, allegedly about 400 feet (121 meters) across, looks like an oval-shaped medieval castle or fort with concentric walls, according to conspiracy theorists. The giant circular structure in Antarctica gives strong evidence of a lost ancient city and civilization that once flourished in the South Pole region.

But while some theorists said that the structure was built by advanced extraterrestrial beings, others insist it was built by humans.

The discovery of a giant, ancient artificial structure that appears to have been a castle or fort suggests that an ancient city and civilization could lie undiscovered under thick layers of Antarctica ice, a conspiracy theorist claimed on the blog Ancient Code. The evidence of the existence of ancient civilization structures buried under Antarctica ice compels a review of our understanding of human history and civilization, according to conspiracy theorists. It suggests the existence of a previously unknown phase of human history and civilization in Antarctica much older than the ancient Egyptian and Sumerian civilizations.

Conspiracy theorists speculate that a civilization might have flourished in Antarctica thousands of years ago at a time that the climate of the environment was much different than today. This means, according to conspiracy theorists, that Antarctica was not always frozen wasteland and that the continent was warm enough in the past to sustain large and complex technological human societies that created impressive monuments, such as temples, castles and cities. But we are unable to see the remains of ancient Antarctica civilization today because most of the ruins are buried in thick layers of ice and snow.

But scientific researchers have denied the sensational conspiracy theory claims, saying that the alleged artificial structure, claimed to be a castle or fort, is in fact part of the natural Antarctica landscape known as a sastruga, the Daily Mail reports.

Sastrugi are irregular ridges on snowy surfaces formed through the battering action of freezing winds and heavy snowfall in the polar and cold temperate region.

But conspiracy theorists rejected the explanation offered by scientific researchers, arguing instead that the shape of sastrugi, determined by the direction of wind, is very rarely oval-shaped. The symmetry of the 400-ft structure is also not characteristic of sastrugi. The symmetry shows that it is not part of the natural landscape of the area but an artificial structure created by intelligent designers, conspiracy theorists claimed.

Some theorists insisted that compelling evidence that people have known about lost ancient civilizations on Antarctica for centuries comes from a map drawn in 1513 by Turkish admiral Piri Reis. The map identifies Antarctica landmass unambiguously despite the official version of history that Antarctica was discovered much later.

This is not the first time that conspiracy theorists have claimed the discovery of monumental artificial structures buried beneath Antarctica ice. Conspiracy theorists claimed recently to have spotted a pyramidal structure jutting out of ice and snow in Antarctica. According to conspiracy theorists, the perfect geometric symmetry of the structure gave evidence that advanced civilizations once flourished on the frozen continent.

But skeptics dismissed the claim.

"Pictures of the pyramid structures are either photoshopped or cropped pictures to make the mountains look more like pyramids or simply pictures of natural formations called nunataks," skeptical UFO investigator Nigel Watson told the Daily Mail.

"[Nunataks] are mountainous formations created by shifting glaciers and erosion, not by laser zapping aliens."

Contesting the claim by skeptics that the alleged pyramidal structure was a natural feature of the Antarctica landscape called a nunatak, conspiracy theorists argued that the symmetry of the structure, which makes it stand out against its natural environment, proved that it was an artificial structure.

The Inquisitr reported that conspiracy theorists claimed that the U.S. Secretary of State John Kerry visited the Antarctica recently to see the ruins of ancient civilizations and underground facilities built by an alleged U.S. secret space program being run in collaboration with technologically advanced alien races under top-secret treaty agreements.

[Featured Image by Wollertz/Shutterstock]