The St Louis Arch is one of the high points in Missouri. Going to the top of it is mind bending, and the museum at the bottom is very interesting. Do yourself a favor and visit this momument at least once.
Skywalk on Tianmen Mountain, China. Stretching around a cliff on Tianmen Mountain in China, the skywalk offers incredible views of Hunan province's lovely landscapes. For those with no fear of heights, the skywalk is 4700 feet up the mountainside.