Various ufologists and experts claim that there are numerous entrances leading to subterranean constructions on Mars. Are these extraterrestrial complexes or human settlements?
The Curiosity rover took the pictures you see below.

As you can see, these “doors” are clearly visible and seem to serve as entrances to a variety of unidentified installations.

The strange oddity that the Curiosity rover just observed may be one of these formations. One of the pictures included something that seemed to be a dome on the background.
There are rumors that the dome may have apertures or windows. Perhaps extraterrestrial relics or entrances to a base underground?
The video below shows another entrance to what appears to be an alien facility on Mars.