Seems like just about anything you can think of has been spotted on Mars: pyramids, floating spoons, lizards, crab monsters, even "a woman. Now, some people believe they've found a massive Stonehenge-like formation sitting in the middle of a small hill on the Red Planet.
Call it Marshenge.
Indeed, the raw NASA image shows a circular formation of stones or boulders atop a hill. It can be seen here, lower right of center:
"Could the builders of Stonehenge have visited Mars, and did they build the same thing there?" asks the narrator, who uses a computerized voice. "Or is this just another face on Mars illusion?"
Here it is even closer:
The scale of the image is not given, so while these could be Stonehenge-sized stones, they could also be much larger rocks. Either way, many "mysterious" objects seen from space at one angle look much less mysterious when viewed from other angles and with better resolution, such as the so-called "face" on Mars the narrator mentions.
An image snapped by NASA's Viking 1 spacecraft in 1976 revealed a formation that looked very much like a human face carved in stone:
However, a more detailed image taken by the Mars Global Surveyor spacecraft in 2001 showed just another Martian hill: