Saw a show on Discover or History channel that was really thoughtful. It showed ancient ruins that were constructed out of huge blocks of stone. We're talking over 100 ton pieces. Some of the ruins are around 6 to 8,000 years old. One located in Mexico shows amazing fit and detail work. It is just crazy to believe crude stone age tribes could have quarried, carved, and assembled these things. Some could not be done today with the machines and techniques we have available. Some details about the great pyramids are also mind boggling. The people would have had to quarry, carve, and transport and lay about 5 stones every second for a few years. Yes that was before labor unions and OSHA, but the Egyptians didn't even have the wheel.