The Face on Mars
Cydonia was first imaged in detail by the Viking 1 and Viking 2 orbiters. Eighteen images of the Cydonia region were taken by the orbiters, of which seven have resolutions better than 250 m/pixel (820 ft/pixel). The other eleven images have resolutions that are worse than 550 m/pixel (1800 ft/pixel) and are of limited use for studying surface features. Of the seven good images, the lighting and time at which two pairs of images were taken are so close as to reduce the number to five distinct images.
In one of the images taken by Viking 1 on July 25, 1976, a 2 km (1.2 miles) long Cydonian mesa, situated at 40.75° north latitude and 9.46° west longitude, had the appearance of a humanoid face. When the image was originally acquired, Viking chief scientist Gerry Soffen dismissed the “Face on Mars” in image 035A72 as a “trick of light and shadow”.
Later and improved images clearly identified the top of the mesa as the top of a mesa.
As is the wont of Astronomers, they nicknamed the mesa “The Face”. Naively, they thought this name would be " a great way to engage the public." Once the press got hold of it the whole affair blossomed into a conspiracy theory about NASA suppressing evidence of an alien artifact on Mars. Of course geologists and astronomers regularly nickname features after favorite pets, bits of machinery, or anything else they bear a passing resemblance to.
This hasn’t stopped generations of ufologists and New Agers from weaving the Face into their particular mythologies however, and on modern Mars the Face continues to attract the lunatic fringe, along with the associated ‘Alien City’.