Cahokia Mounds

A thousand years ago Cahokia was the largest city anywhere north of Mexico, home at its height to perhaps twenty thousand people, more than London at the same date, and its people moved an extraordinary quantity of earth by hand to build it. Monks Mound, the largest earthwork anywhere north of Mexico, rises in four terraces to about thirty metres with a footprint bigger than the Great Pyramid's, and around it stand dozens more mounds, a reconstructed timber circle used to track the sun that researchers nicknamed Woodhenge, and the outline of a great plaza. The city was abandoned before Europeans arrived and nobody is certain why. Climbing Monks Mound and looking out at the St Louis skyline across the floodplain puts a thousand years into one view.

What you actually see

• Monks Mound - the largest earthwork north of Mexico, climbed by a stairway.
• Woodhenge - the reconstructed timber circle aligned to the solstices.
• The interpretive centre - the city's story and a reconstructed village scene.
• The mound field - dozens of surviving mounds across the site.

When to go

Spring and autumn are the most pleasant; the site is open in all seasons but summer is hot and humid on open ground with no shade. Sunrise and sunset gatherings at Woodhenge mark the solstices and equinoxes. Check the interpretive centre's days, as they have varied.

Honest expectations

It takes imagination: this is grassy mounds rather than stone architecture, and without the interpretive centre or a guide the scale of what stood here is easy to miss entirely. The setting is unglamorous, hemmed by highways and suburbs. The climb up Monks Mound is a steep stairway. It deserves far more visitors than it gets.

Nearby

St Louis and the Gateway Arch are fifteen minutes west across the river.