[Azred]

Many early civilizations had similar technologies and built similar structures (megalithic buildings, pyramids, etc). The two main theories as to why this is the case are "parallel development" and "diffusion". Ancient lost civilizations are the "logical" backing to the diffusion theory--the technology was centered in the lost culture, then when it was destroyed the survivors scattered all over the world, taking the technology with them.
One intriguing hypothesis I read speculated that Atlantis (for lack of a better name) could be buried under the Antarctic ice (several kilometers thick in places). The most compelling idea in this hypothesis is that the other continents are relatively equally accessible from Antarctica; Antarctic explorers could have easily visited all other continents.

It is generally accepted that ancient civilizations must have had some sort of technological knowledge which has been lost. The question about how the pyramids were built has still not been answered completely. Don't forget about the places in South America where the megaliths have 400-ton blocks at 12,000 feet (3.65 km) of altitude--even today that would be a nearly impossible feat. I won't go into a discourse about the hypothesis that these building might have been poured into place with a primitive "concrete" (which is just crushed rock, sand, lime, and water). The question of the blocks fitting so tightly that a playing card cannot be inserted between them has been answered--the blocks are held in place with metal pins; this, of course, creates another question--how were the metal pins put into the blocks? Did those ancient civilizations have mobile metal forges?

*whew* I did ramble on a bit, didn't I? [img]graemlins/petard.gif[/img]