I just saw this video and my mind was completely blown, the only description on the video’s page is this:

Originally built in 1901, this walkway now serves as an aproach to makinodromo, the famous climbing sector of El Chorro.

This really doesn’t do it justice, just check this out:

I think I could probably have followed along up to the point where he WAS WALKING ON RUSTY PIPES THOUSANDS OF FEET ABOVE SOME ROCKS.

Balls of steel.

late edit: I just realized that this is exactly like a level out of Half Life