The borrow pits — the areas from which earth was excavated for mound construction — are themselves significant landscape features.

The lakes and ponds that appear in the Cahokia area today are, in many cases, the water-filled remnants of ancient borrow pits.

Centuries of earth removal created depressions that eventually filled with water, and those features have persisted in the landscape as distinctive markers of the city’s former extent.

The construction of the palisade wall that enclosed the central precinct was itself a massive project.

The wall, which was rebuilt at least four times, required tens of thousands of wooden posts, each of substantial diameter — the post holes that indicate the wall’s former position show openings large enough for timbers 30 to 50 centimeters in diameter.