A guy named David Martines announced on YouTube that he'd discovered an "anomaly" which is clearly a secret Martian base, just by using Google maps. You can see what he's calling the base in this image, taken from Google, above.
I call it Bio-station Alpha, because I'm just assuming that something lives in it or has lived in it. It's very unusual in that it's quite large, it's over 700 feet long and 150 feet wide, it looks like it's a cylinder or made up of cylinders. It could be a power station or it could be a biological containment or it could be a glorified garage - hope it's not a weapon. It could be a way station for weary space travelers. It could also belong to NASA, I don't know that they would admit that.
If only NASA really did have a secret Martian base! That would rule. Unfortunately, I'm afraid that this is just like the time people found the lost city of Atlantis via Google maps, as well as a ghost via Google Street View. Probably just a glitch. Though if it were a ghost in a Martian Atlantis . . . well, that would be real.
(Thanks for the tip, Lord Illundiel!)