We spent the afternoon of January 10, 2012, visiting the UNESCO World Heritage Site (1983) at Machu Picchu. More fantastic stone work is shown in this photo. Machu Picchu was built on a large wedge-shaped fault block called a graben that was formed by a gradual downward subsidence of the block created by two parallel running faults. This plus erosional processes created the topographical area that the Inca selected for building Machu Picchu. Gary R. Ziegler states that photos taken by the Hiram Bingham expeditions in the early 1900's compared with recent Machu Picchu photos and showed no settling of on-site structures. Temperatures were in the low 70's with humid conditions and low hanging clouds drifting in over the Andes.