Are these our experimental craft, or are they reverse engineering alien craft...  
Recommended Reading
The Mars Mystery: The Secret Connection between Earth and the Red Planet
The Message Of The Sphinx: A Quest For The Hidden Legacy Of Mankind
Monuments of Mars: A City on the Edge of Forever
Nephilim: The Truth is Here
The Enterprise Mission
Richard C. Hoagland, founder of The Enterprise Mission, recipient of the Angstrom Medal, former science advisor to CBS News and Walter Cronkite, author of "The Monuments of Mars", co-creator of the "Pioneer Plaque", originator of the "Europa Proposal", and principal investigator of The Enterprise Mission
D&M Pyramids of Mars
The following article is the result of work done in 1988 and 1989 concerning an enigmatic landform located in the Cydonia Mensae region of Mars. The object pictured here is five-sided, pyramidal, and located a few miles from the Face on Mars. Like the Face, the D&M Pyramid is part of a complex of unusual landforms that may be the product of intelligent design.
Ancient Astronauts
American Astronomer Tom Van Flandern, in his June 1998, ‘Best Evidence Yet for Planetary Artifacts’, analysed the various features of the ‘Face’ and concluded that:‘the combined probability of simultaneous chance occurrence of all the features of the Face mesa alone described in this article and predicted a priori by the artificiality hypothesis is 0.0000000000000000000000000000001.’
Martian Anomalies
More information on Martian anomalies
Mars Global Surveyor
MGS "Mars Gloral Survey", MOC "Mars Orbiter Camera" and Viking images of the "Face on Mars".
Cydonia-Mars, -the stones of fire-
A very interesting site connecting the Spinx to the Mars Face.
The "Forgotten" Anomalies of Mars
Recent high-resolution images from NASA's Mars Global Surveyor spacecraft have failed to confirm the theorized artificiality of the Face on Mars, or that of its neighboring "City," beyond a reasonable doubt.