This hike is not difficult, unless you have a problem with sheer cliffs, crumbling concrete paths, gaping holes exposing hundreds of feet of vertical drop, and even completely missing sections in the 1-meter-wide trail.
This artificial walkway, finished in 1905, was built to give workers access between the hydroelectric power plants at Chorro Falls and Gaitanejo Falls. King Alfonso XIII took a walk along it in 1921, hence the name. It ascends more than 100 meters (330 feet) and is falling apart. Many have died on this trail, and there are safety lines along the path for attaching harnesses.
This popular daredevil path is undergoing much needed renovation, and is expected to reopen in 2014. More information is here.