Remember that Martian face imaged from space by the Viking Orbiter back in 1976? A number of orbiters have imaged this plateau over the past decade. Check out these new perspectives at this post on Universe Today. It includes an optimal hiking route around the jawline, across a cheek, and up a nostril to get to the top.
So if it’s not a monument to provide sales of tabloids and speculative books on ET architecture, what is it? Probably a lava dome.
Image above from the Mars Reconnaissance Orbiter; credit: NASA/JPL/University of Arizona.