COLLINSVILLE -- Visitors to Cahokia Mounds State Historic Site on June 23 will get a glimpse of a 1,000-year-old sacred celebration of the summer solstice at "Woodhenge."
Woodhenge is an arrangement of posts standing in line with sunrise on the longest day of the year June 21; the shortest day, in December, and the spring and fall equinoxes, when day and night are the same length.
These were sacred days to residents of Cahokia Mounds, when it was the largest city north of Mexico.
Visitors to the site should arrive by 5:20 a.m. to hear an archaeologist explain the monument's discovery and function.
The site is in Collinsville in southwest Illinois, about eight miles from downtown St. Louis. It is administered by the Illinois Historic Preservation Agency.