Still jaw-dropping after all these years, the Giza Pyramids won't disappoint. Built in 2,500 B.C. by a work force 10,000-strong, their architecture, shape and geometry inspire awe. Part of a UNESCO World Heritage site, the Giza Pyramids comprise a set of 3 tombs. The largest, the Great Pyramid, is the oldest, and one of the original Seven Wonders of the Ancient World. Note: Most guidebooks suggest visiting with an Egyptologist as guide.