HiRISE captured this image (in 2007) of an eroded mesa made famous by its similarity to a human face in a Viking Orbiter image with much lower spatial resolution and a different lighting geometry.
Compared to the original Viking image, HiRISE shows incredible detail, even from 300 kilometers above the surface.
Written by: Alfred McEwen (28 July 2010)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_003234_2210
Image: NASA/JPL/University of Arizona