Came upon this . It's a brightcove.tv video of a now broken down cliff side canyon trail.
"Originally built in 1901, this walkway now serves as an approach to makinodromo, the famous climbing sector of El Chorro."
Most definately not open to the public, me thinks.
The footing is trecherous, parts of it looks like it could be a scene from a pc game like Myst... or something newer. The music fits this flash video nicely.
A lot of browsers won't play this link, but MS Explorer will. Worth firing up Explorer for. If the video stalls at "loading"... click the link and copy and paste into MS Explorer.
El camino del Rey - Brightcove