the famous sundial, day 4 - machu picchu
The famous sundial. The four corners of the rock on the top point to the exact position of North, East, South and West. I verified that with my watch compass (the front corner in the picture).
It was not known that Incas have knowledge of the compass, how they figured that out was a mystery.
Another interesting thing about the sundial was at noon of June 21st, the upper rock will cast no shadow upon the lower rock. This usually only happens to places on the equator (because the sun was directly above). Obviously the rock was tilted in a very precise position to achieve this effect.