Buried Polar Cities of Mars:
Ancient Martian Civilization Evidence #487-x9
Image Credit: NASA/MALIN/JPL
Link to understanding dethawing martian dunes: http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1056.pdf
The thawing of polar layers, creating swiss cheese of the Martian surface,can give the illusion of cityscapes.
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