It’s called El Caminito del Rey, which I guess would be the king’s little road.
The made us wear helmets and gave us a radio to listen to the guide. We didn’t necessarily want a guide, but you have to buy tickets in advance. We got ours the week before and all that was left was the guided tour. Not too bad though; we hung back and kept the the group (12 people or so) within earshot.
The middle of the hike was full of spectacular views in their own right, as well as views through the canyons on each side.
With a video of the bridge crossing to boot!
Wonderful hike. Don’t plan on getting sweaty, but plan on using your eyes. Highly recommended!