CLAIMS an ancient civilisation said to have once populated Mars took a step forward today after alien chasers said they found the remains of a walled city in new NASA images of the Red Planet. UFO seekers are claiming the ruins can be seen hidden among rocky Martian mountains. The photos, taken by NASA's Curiosity Rover, have sparked fresh claims there may have once been intelligent life on the planet. An alien conspiracy theorist revealed the suggestion in a blog post titled "Alien City Ruins on Mars? In Official NASA Images". They wrote: "In the last couple of years, the number of images showing alleged structures on the surface of the red planet have quadrupled. "In fact, nearly every single image beamed back by NASA's rovers on Mars seems to show at least one particular 'object' which appears to be artificially carved or created. "While most of these objects are the result of pareidolia, other findings cannot be dismissed so easily." Pareidolia is when the brain tricks the eyes