Earthen Mounds

Flat-topped pyramidal temple mounds are found in southern Mississippi, as well as Georgia, Oklahoma, Wisconsin, and probably beyond. Reaching 70-80 ft (21-24 m) in height, they were built in clusters, often around a central plaza. Many of them have log stairways or ramps leading up the sides to the temple, which was constructed of mud and thatch and may have housed an eternal flame.

The most famous temple mound complex is the Cahokia Mound site in southern Illinois. Covering more than 16 acres (6.4 ha), Cahokia Mound is larger than the largest pyramid in Egypt. It contains as many as 67 mounds. Monk's Mound, the largest of these at more than 50 ft (15 m) high, was the site of the temple that was probably occupied by the ruling family. Its construction may have required more than 300 years of labor and more than 22 million cubic feet of earth.

Also at the Cahokia site is a mysterious structure known as Woodhenge. Similar to Stonehenge in construction, it consisted of a circle of red cedar posts that may have been used as a solar calendar by the priests to mark off specific astronomical events. These would have included the two annual equinoxes and the winter and summer solstices. The equinox is the point at which the center of the sun crosses the celestial equator and day and night are of equal length. The solstice is the point at which the sun is at its greatest distance form the celestial equator and appears to be farthest north or south in the sky. Knowledge of these events helped the priests to determine when to plant crops.

High-ranking members of society continued to be buried in the temple mounds with an elaborate accompaniment of grave goods, including a copper mask of the "long-nosed God," similar to that made by the ancient Maya. Most people, however, were buried in cemeteries outside the cities.