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. 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 (note the restoration workers). The Torreón or the Temple of the Sun can be seen on the left side of the photo. It was built with polished and tightly fitted granite rocks in a spiral shape with windows of various shapes and sizes built into it. The windows appear to have been deliberately placed to provide views of particular astronomical objects (Collca, an Andean constellation, and the Pleiades) and events (summer solstice). Temperatures were in the low 70's with humid conditions and low hanging clouds drifting in over the Andes.