Face Image, April 2001, MOC image
http://www.msss.com/mars_images/moc/extended_may2001/face/
Nature, of course, does not do straight lines or Bezier curves on a three mile scale. Aside from eye sockets, nostrils, lips, and a helmet or head dress of some sort involving smooth curves, we observe the following: Nobody would build such a thing with carved stones; what you would do is pile stones into the general shape you wanted and then pour some sort of a hard facing material like concrete over the stones. Assuming such a structure were many thousands of years old and given a planet on which sand and wind were in plentiful supply, you would expect to see that hard facing weathered away on the windward side and falling away in slabs on the leeward side. In the picture thus obviously, the wind and sand come from the lower left.
D&M Pyramid, 2003 image
http://www.mactonnies.com/dmphotos.html
Nature does not do five-sided pyramids with multiple equilateral triangles either. The official word from NASA is still that this is a natural land form. Unofficial word is that NASA and the JPL are about evenly split with about half of the researchers willing to believe their eyes and the other half still caught in the paradigm bottle.
There is of course no way to picture Mars ever having been habitable enough for this stuff to get built given standard theories about the history of our solar system. That basically means that those theories are wrong, and a lot of NASA types still do not want to go there. Again, they were able to get by with that when we were the only nation capable of getting to Mars; that is no longer the case.
Oh yeah, before anybody else says it, there will always be one or two losers piping up claiming that all they see in those images is rocks, that's also inexcusable in an age when Walmart sells good reading glasses for $15.