A complex ramp was used to move the enormous marble blocks up to the Acropolis. Some of the largest blocks weigh over 10 tons.
The first Great Wall was built from mud and reeds over 2,000 years ago. As warfare developed, the wall had to be improved and strengthened.
The Great Pyramid of Giza was the tallest structure on Earth for more than 3,500 years! Workers had to cut and lay more than 200 blocks a day in order to meet their deadline.
Take a virtual tour of the final resting place of the boy king.
The elaborate defenses of Egyptian tombs - and how clever thieves got around them.
See inside the secret tomb beneath the Pyramid of the Feathered Serpent.
See how the Sphinx originally appeared, and how it demonstrated the power of the pharaoh Khafre.