We spent the afternoon of January 10, 2012, touring Machu Picchu, a UNESCO World Heritage Site (1983). Incan stone masons were renowned for their building skills. No mortar was needed because the stones used in construction were precisely cut and closely wedged together. Earthquakes in this seismically active area cause the stones in an Incan building to 'dance,' i.e. bounce through the tremors and then fall back into place without destroying the building (see buildings in the center of the photo). It has been estimated that 60% of construction done at Machu Picchu was done underground to prepare the site with deep building foundations and crushed rock for drainage purposes. All of this has kept the site 'relatively' intact. The granite stairway in the center left of the photo leads up to the Intihuatana Stone which sits at the highest point within the main ruins. Part of the granite rock quarry can be seen at the lower left to center of the photo. Temperatures were in the low 70's with humid conditions and low hanging clouds drifting in over the Andes.