9. Pyramids of Giza, Egypt
The most famous of the structures at Giza, near Cairo, the Pyramid of King Cheops was built around 2650 BC from 2.5 million blocks of limestone. Its sides are oriented exactly to the north, south, east and west. The Chephren pyramid, built by Cheops’ son, is similar in size and incorporates the entrances to a burial chamber that still contains the large granite sarcophagus of King Chephren. The pyramid of Mycerinus is smaller than both and all three are surrounded by other smaller pyramids and dozens of tombs.