The face of Mars is a landform in the region of Mars called Cydonia. Because of limited photographic resolution at the time, the Viking 1 photo from 1976 makes it look like a face. Some people say that the face was made by aliens, but there is scientific evidence against this.

The reason it looks like a face is because the 1976 photograph was blurred. A later photo taken in 1998 makes it look less like a face, but some claimed it may still be a face due to the fact that the photo was taken in cloudy weather. In 2001, a photo was taken that did not look like a face at all, but a natural landform such as a butte or mesa. It is unlikely that aliens would make a landform like this, because it has no actual structure. Statues and monuments made by humans are meant to look like something and tend to be uniform in shape. The Face on Mars, in more recent photographs, doesn't look like anything but what it probably is, which is a natural landform.

Another reason it is probably a natural landform is because theories that it was made by aliens were created purely by the public. There is no actual evidence that would suggest that the the face on Mars was made by anything that was alive, other than the fact that a blurry photograph taken 40 years ago makes it look like a face. There is not any evidence to suggest that Mars would have even been able to support life in the past or is able to support it now.

The evidence against the Face on Mars being made by aliens or an ancient civilization on Mars is far too substantial to be dismissed in favor of speculation by conspiracy theorists or depictions of it in fictional movies. In fact, the face on Mars strongly resembles landforms on Earth that were formed naturally. The most likely explanation for the face is that it's a natural formation that looked like a face in a photograph, and that anything special about it is purely speculated. It is completely illogical to think that an optical illusion means anything, and until there is evidence to suggest that it isn't, the Face on Mars is probably nothing more than a hill.