Signs of an ancient civilization in Antarctica was discovered and looted

In the image taken in 1993, you can see a small dark spot, possibly a building, which would have been removed some time later, as can be seen in the image captured in 2013. It can also be seen in the photo of satellite the huge structure with several large ridges.

The site appears to have been extensively excavated, and vehicles and several tracks in the snow leading to it are also visible. This suggests that there was activity from some entity with sufficient resources here. There was also a landing strip for airplanes near the site. This would indicate that they have been in place for a long time. And it was the only way to transport the equipment for the due study of the ruins.

Conspiracy theorists believe that scientists must have excavated it to try to find out what is inside the bizarre structure, and heavy machinery such as tractors would have been used to clear the area.

From what can be seen in the image, it is not very clear if what they have found is an underground base, or a building covered by snow and ice.
Apparently, after being looted, the place was abandoned, as can be seen in the image taken in 2016, and which is the last one taken from the place.

Is this proof that an unknown ancient civilization existed at the south pole? If so, who were its builders and how old is it? What was found inside? Why has nothing been officially announced about it?