I think apachama is referring to

Baghdad Batteries
http://en.wikipedia.org/wiki/Baghdad_Battery

Antikythera Mechanism
http://en.wikipedia.org/wiki/Antikythera_mechanism

Vitrified Desert Glass and Vitrified Forts
http://jcolavito.tripod.com/lostcivilizations/id9.html

The Nazca Lines
http://en.wikipedia.org/wiki/Nazca_lines

And the like. I agree that it is very interesting, but purely from a mythological standpoint. I love what conspiracy theories and the interent have done to myth making. Some people feel that unexplained mysteries need fantastic myths as explanations. It is like backing up in your car, and automatically assuming there is a unicorn hiding in your blind spot.