You want old? How about the Pyramid in Giza, Egypt, which was built in 2570 BC or close to 4600 years ago and it was the tallest man-made structure for 3800 years. But amazingly enough, it was not the tallest pyramid ever. The pyramid in Cholula, Mexico, built by the Toltecs near the present city of Puebla, Mexico, was taller but as the Toltecs disappeared, the jungle took over it and when the Spaniards conquered Mexico, they thought it was a hill and built a church on top of it. It wasn't until the 20th century when they finally figured out it was not a hill, but a pyramid.