In July, 1976, Viking Orbiter 1 was acquiring images of the Cydonia region of Mars as part of the search for potential landing sites for Viking Lander 2.
On 25 July, 1976, it photographed a region of buttes and mesas along the escarpment that separates heavily cratered highlands to the south from low lying, relatively crater-free, lowland plains to the north.
Among the hills was one that, to the Viking investigators scrutinizing the images for likely landing sites, resembled a face.
Owing to the importance of the landing site search, and with a desire to provide the public with at least one familiar-looking landform amid the craters and exotic terrains found all over Mars, an image including the face-like hill was released as part of the Jet Propulsion Laboratory's public relations effort. The text of that release notes the face-like hill.
Subsequent to this release, some people have argued, mostly in the lay literature, that the face-like hill is artificially shaped. Although their argument has been expanded to a host of nearby features, none commands public interest like the "Face."
Researcher Richard Hoagland believes the face to be an alien with a link between Earth and Mars linking with the patterns of Sacred Geometry