Reconstruction of Cahokia's Woodhenge. This was an ancient observatory. The standing timber posts were placed in the existing post-holes. Woodhenge was modified and rebuilt several times over the approximately 300 years it was in use. This view is facing Northeast. Note the flat top of Monk's Mound directly to the East of Woodhenge. At times, the Sun would appear to rise directly from the top of the mound, where the Chief's residence and temple were located.
Monks Mound as viewed from ground level, the largest structure at Cahokia and an imposing focal point for the city's design. Modern stairs have been built in the approximate position of the original stairs, providing access to the top of the mound. This wide angle view is a mosaic created from several photos. Unfortunately it does not convey the true scale of the structure, created entirely by manual labor over many years. The center of this image is looking Northwest.
It was a society based on agriculture, supporting up to 20,000 inhabitants. The people who constructed these monuments were representative of the Mississippian Culture. The settlement was originally surrounded by a tall barricade, a wall made of large timbers and clay. The largest of the mounds, Monks Mound, towered over the surrounding landscape. It was over 100 feet high, 955 feet long, and 775 feet wide. The sides of the mound have slumped over the last 1000 years. In 1735, French missionaries built a small chapel on the south end of the terrace. While the site was again abandoned a couple decades later, Monks Mound gets its modern name from these inhabitants. Later, in the 1860s, new owners began to see the ruins as a site worthy of study and preservation.
Among the discoveries made at Cahokia, were the remnants of post holes tracing a circle over 450 feet across. Constructed of large timbers, the circle was a Solar Calendar, useful for predicting and observing the rising sun at the Winter and Summer solstices, as well as the Vernal and Autumnal equinoxes. Agricultural societies throughout history have taken great interest in predicting the seasons and there are many examples from across the globe of similar sites. Cahokia would have been no different. Successful growing seasons and high crop yields were vital for short-term needs and long-term stability. Only with effective farming practices could such a large city afford a specialized workforce creating industries of artisans, traders, hunters, and priests, all evidenced by numerous other artifacts unearthed in Cahokia. It is worth noting that Woodhenge at Cahokia lies approximately 1 mile due west of Monks Mound. Size alone suggests this mound, the largest in Cahokia, was likely of great importance. However, when viewed from Woodhenge, the Sun would appear to rise over Monks Mound every morning. The symbolism is hard to ignore and is certainly no coincidence.
Woodhenge at Cahokia, like other similar circles dating back to very ancient times, was important for watching the motions of the Sun, and possibly the Moon and stars. There have been no written records or accounts found of the cultural practices of ancient Cahokia, but the obvious alignments of the positions of the Sun and Moon with the top level of Monks mound suggest that this was an astronomical device. It would have been a practical instrument for timekeeping as well as a source of deeper cultural meaning for the people of this once flourishing civilization.
By Chad Quandt
While much has been written about the astronomical functions of monuments like Stonehenge in Great Britain, or the Pyramids of Giza, the Woodhenge of Cahokia is another reminder that all cultures throughout history have tried to interpret the sky for understanding. Astronomy runs deep in our species. It has been and continues to be a quest to know how and why things are the way they are.
Did the Cahokia tell stories about the stars in the night sky? Did they name the stars and arrange them into groups, either for convenience or to represent something else important to their daily lives? Did they watch the cycles of the Moon, counting the days between phases? Was their leader, the Chief, descended from the gods? Did he or she watch over them throughout the day, just as the Sun did after climbing from the temple on Monk's Mound? While we may never know the details of Cahokian astronomy, what has emerged suggests they were certainly regular participants in the Oldest Show on Earth.
This relief map resides at the Cahokia visitor center and depicts the layout of the settlement, including the location and relative sizes of many of the mounds that still exist today. The largest was Monks Mound, the site of the Chief’s residence. Note the circular feature at the far left. It is clear that a great deal of planning went into the layout of the various structures.
One thousand years ago, there was a flourishing city in the fields and hills east of St. Louis, Missouri. Today, the remnants of over 100 mounds represent the principle features of this lost civilization. Unlike most of the widespread mound building, common throughout North America in pre-Columbian times, these mounds were huge, serving as platforms for important buildings, houses, or temples. Today the settlement is known as Cahokia, a name given not by those who built it over a span of 300 years, but those who later inhabited when first contact was established with Europeans, long after they the builders had disappeared.
Last Updated 17 July 2020.
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