The Luxor Hotel (shaped like an Egyptian Pyramid) in Las Vegas is 36 stories tall, and required more than 150,000 cubic yards of concrete, 6,000 construction workers, and 18 months to build. It takes a specially designed window washing device 64 hours to clean the sides of the pyramid, which are covered by 13 acres of glass. The Luxor atrium is the world's largest and could comfortably hold nine Boeing 747 airplanes