Cahokia is the Native American site in Illinois that includes the reconstructed Woodhenge solstice sunrise marker.
Cahokia was a major Mississippian cultural center near present-day Collinsville, Illinois. Its people built earthen mounds, plazas, and several large timber circles known collectively as Woodhenge. The circles were arranged with posts marking important sunrise positions, including the summer and winter solstices and the spring and autumn equinoxes.
The reconstruction represents Woodhenge III, one of the later versions identified by archaeologists. Built in 1985, it places posts into excavated original postholes, including a central observation post. From the circle’s center, observers could watch the sun rise behind specific posts at seasonal turning points.
A common mix-up is confusing Cahokia with better-known astronomical sites such as Chaco Canyon or Mesa Verde. Cahokia is not a single mound but a large archaeological landscape, and Woodhenge was made of timber rather than stone. The site still hosts public sunrise observations at solstices and equinoxes.