lostmy4digitUID writes: As a profesional engineer and a historical hobbyist I have have been researching some of the greatest ancient accomplishments. What i found was that some of the greatest accomplshments are not as well know in the mainstream as they should be. When we hear about ancient engineering we hear about the Giza pyramids, Stonehedge, or the Nazca lines. I am contemplating writing a book about the lesser known but far more impressive ancient accomplishments such as the Ba'albek stone in Lebanon which weighed about 1200 tons (2.4 million pounds) or the construction of Pumapunku in Bolivia which displays perfect 90 degree angle cuts with out any tool marks ( supposedly built by a civilization that was illiterate). There are many more examples such as the Antikythera mechanism which is arguably the worlds first complicated machine. I would like to ask the group think machine for any other examples and possible explanations for such advanced engineering in such prinitive times.