Cydonia is a region on Mars. It lies in the planet's northern hemisphere in a transitional zone between the heavily-cratered regions to the south and relatively smooth plains to the North. Cydonia itself is covered in numerous mesas and may have been a coastal zone if planetologists are correct in believing that the northern plains were once ocean beds.

One of the Cydonian mesas took on the striking appearance of a human face in a photo taken by Viking 1 in 1976. Whilst generally held to be an optical illusion, some people interpret it as evidence of a long-lost Martian civilisation. Later, better, photos revealed a very ordinary-looking mesa with little resemblance to a face at all.


Cydonia is also the name of the genus to which the quince belongs.