The Caminito del Rey is famous for some hair raising parts, crumbling cement and rusted handrails (I didn't try...)I encountered a number of passages on smooth rock face above the sea or void I didn't enjoy at all.
I had a different scary moment on my last hike in the Vosges area, where the trail crosses a main road at the top of a pass. Come out of the woods after a steep way down, cross the road dodging traffic, the other side is a big concrete abutment (?) wall, with a vertical metal scale. Go up the scale slippery in the pouring rain, with trucks and cars rushing, full speed, two feet behind your butt...Vanish into the woods again with a relieved sigh.