Cahokia
Another large feature at today's Cahokia is Woodhenge. The Cahokia Woodhenge was a large circle of timber posts located roughly 850 m (2,790 ft) to the west of Monks Mound.  Excavations found the original placements of many large timber posts. In 1985, a reconstruction of Woodhenge was built with the posts being placed into the original excavated post positions. The circle, which has 48 posts in the circle and a 49th central post, has been used to investigate ancient astronomy at Cahokia.