Built for the pharaoh Khufu about 4,500 years ago, the Great Pyramid at Giza is considered a wonder of the ancient world. Credit: Nina Aldin Thune, CC Attribution 2.5 Generic ================================================================================================== The Great Pyramid of Giza may be a Wonder of the Ancient World, but it's not perfect: Its base is a little lopsided because its builders made a teensy mistake when constructing it, new research reveals. The west side of the pyramid is slightly longer than the east side, scientists have found. Although the difference is very slight, it's enough that a modern-day research team, led by engineer Glen...