Sun Temple and Sun Gate

Sun Temple and Sun Gate, originally uploaded by davidagalvan.

The Inca had a fairly good understanding of astronomy. This shot, taken at Machu Picchu in Peru, shows the so-called "Sun Temple" in the lower left. At the winter solstice (well, the summer solstice for them, since Peru is south of the equator), the sun would rise right in that little notch in the horizon, and sunlight would pass neatly through one of the windows in the sun temple. They had another window to mark the opposite solstice.