Rio Grande River Gorge Bridge, NM

I assumed the Rio Grande River cut this gorge like the Colorado river cut the Grand Canyon, but actually the valley was formed first and the river followed. This area sits between two tectonic plates and a bazillion years ago the shifting of the earth's crust formed the gorge. The bridge is the fifth highest span in the U.S.

 

The surrounding area at the top. You wouldn't want to be stumbling around in the dark because there's no indication that a gorge is nearby. 

 

The Rio Grande from the valley.