Life Changing Historical Sites

Traveling around the world, I get to see the best the world has to offer in terms of man made and natural sites. One thing that always amazes me are the ancient historical sites I visit. You gaze up at these structures built thousands of years ago, without the aid of any technology or modern construction, and think to yourself "How did they do that?" It shows what people can accomplish when they are driven. I find that these sites inspire the most awe: