Stone circle with intihuatana, probably from Inca period, Lake Umayo in background, Sillustani, Peru

Intihuatana literally means "hitching post of the sun", and was a standing stone used by the Incas to determine the seasons. They were a feature at several Inca sites (the most famous one is the carved stone block at Machu Picchu); according to records from the mid 19th century there were 2 stones at Sillustani surrounded by a complete stone circle.