Stunning, square-shaped features discovered on a NASA image from the Planet Mars , give the strong impression of artificial walls and ruins - and researchers speculate they could be the ancient remains of a Martian city.
The image in question NASA ref ESP_019103_1460  was taken in August 2010 by the HiRISE camera on board the Mars Reconnaissance Orbiter spacecraft, and researcher Javed Raza came across the artificial-looking square features while studying the image. His report and image analysis  was later circulated amongst the wider Mars enthusiast community by author George J. Haas of The Cydonia Institute .
Prompted by the intriguing images posted of the structures, "The Mars Archaeology Archive" decided to analyse the image .
"The apparent 'walls and ruins' appear convincing when they are viewed in isolation. However, the surrounding geological terrain reveals two factors that negate the likelihood of them being artificial:
1. The straight edges that make up the square structures, run parallel to widespread linear striations in the landscape that are clearly of a geological nature.
2. There are many more similar-shaped features that are more mound-shaped and rounded, up to 400 metres and beyond the target location. These more prevalent structures appear to 'grow' from the more obvious square structures, which strongly suggests they share a common geological origin.
Initial conclusion: the square artificial-looking walls and ruins, are likely to be geological in nature. Possibly eroded mounds of rock/sediment that are beginning to form a kind of tessellated pavement structure."
M J Craig
Mars Archaeology Archive
1. Image Analysis Report MAA-041 Ruins of a Settlement? #2
2. NASA image source
3. Javed Raza Report & Image Analysis
4. Cydonia Institute post "An archaeological discovery in Atlantis Chaos" http://thecydoniainstitute.proboards.com/thread/131/archaeological-discovery-atlantis-chaos