by Mac Tonnies c. 2000
Granted that the chances of finding "freeways" and "shopping malls" at Cydonia and elsewhere on Mars are based on terrestrial chauvinism, what should we be looking for? Since we're dealing with possible structures conceived by apparent aliens, it may appear that anything we look at in the Mars photographs is a candidate feature for artificiality. I argue that this isn't the case, and that the flurry of brash dismissals and eager endorsements that followed the 1998 Mars Global Surveyor overflights are naive in the extreme.
Features on Mars have been discovered that seem to conform to practical (and aesthetic) criteria (i.e., various crater rim formations suggestive of mining operations). Unfortunately, we must rely on circumstantial evidence for the date of these candidate structures. Mark Carlotto, in the revised edition of "The Martian Enigmas," suggests that the Face and City were constructed approximately 30,000 years ago, based on solstice evidence. Prior to Carlotto, Richard Hoagland calculated a date of 500,000 years.
In either case, based on what we know about the planet's geological history, Mars was essentially a "dead" world. Such bleak conditions would have placed certain physical and ecological constraints on any civilization living on Mars at the time, whether it was indigenous (John Brandenburg's "Cydonian Hypothesis") or from elsewhere in the galaxy. Assuming that the "Martians" were biological creatures with needs not unlike our own, what would we expect them to build in order to maintain their presence on an inhospitable world? This is a question of increasing relevance as plans to send our own crewed mission to Mars become more mature and practical.
Specifically, the Martians would have needed to protect themselves from the elements and maximize resources such as heat, water and air. This is exactly purpose of the "Mars Direct"-style habitats now under consideration by NASA.
While plans for manned bases envision a crew of relatively few, a large population such as a Martian civilization would naturally have required much larger habitats. Is this what we are observing in massive formations such as the D&M Pyramid and various formations in the City area? This idea was originally proposed in Richard Hoagland's speculative book "The Monuments of Mars," in which he cites architect Paolo Soleri (a proponent of megascale engineering intended to minimize urban sprawl). Some of Soleri's designs for enclosed cities are pyramidal and kilometers in width.
The City Pyramid and the D&M formation, with their hints of structural detail and similar "starfish" shape, may be enclosures of this sort. This theory gains support from the the Fort, an angular formation adjacent to the City Pyramid that appears to have imploded.