The Inca bridge was restored in 2008.  The cliff was bolted to facilitate the restoration.  The hangers are rated 22kN, but the bolts themselves are only 1/4

The Inca bridge was restored in 2008. The cliff was bolted to facilitate the restoration. The hangers are rated 22kN, but the bolts themselves are only 1/4".    Machu Picchu, Peru -- 1/12/2009