- + 3 Gold.
- +1 Amenity from the first Cahokia Mounds in the city
- +1 Amenity from the second Cahokia Mounds in the city (with Natural History)
- +1 Food for every 2 adjacent districts (with Feudalism) or for every district (with Replaceable Parts)
- +1 Housing
- +1 additional Housing (with Cultural Heritage)
- Cannot be placed next to another Cahokia Mounds
A very solid tile improvement, the Cahokia Mounds are one of 3 city-state improvements in the game that grant Housing (the others being the Monastery and the Mahavihara). This improvement can solve any Housing issues a city may have. Cahokia Mounds are even stronger than the Monastery and Mahavihara since its other bonuses ( Gold, Amenity, Food) have a much wider scope of applicability. In the late game try to build two in every city to take advantage of the bonus Amenity. A fantastic improvement that grants all the essentials to an early empire, the Cahokia Mounds should be the reason why you should definitely devote your Envoy power into Cahokia, the earlier the better. Beware, since Housing, Gold, Amenity and Food are what everyone needs, the competition for Cahokia's Suzerainty will be tough, especially when you do not spawn right next to it.
The Amenity bonus is received even when the improvement is built in a tile owned by the city but outside of its workable range (4th or 5th ring). The Housing bonus is also received but limited to only +1 per improvement, even after Cultural Heritage is discovered (same behavior as the Monastery improvement). This is useful for large cities that are running out of usable tiles.
North American civilizations like the Adena, Hopewell, and Mississipian cultures constructed thousands—perhaps tens of thousands—of earthen mounds over the continent in the centuries before European contact. The purpose of many of these mounds remains mysterious. Some, but not all align with astronomical landmarks. But the greatest of these are the ones associated with the culture at Cahokia.
The largest mound at Cahokia is called “Monks Mound” because a community of Trappist monks built a settlement on or near it in the early colonial era. What the Cahokian citizens called it is unknown to us. The largest part of the structure is about 900 feet long, 250 feet wide, and approximately 20 feet tall, and is cleverly engineered to minimize the shrinkage and swelling associated with the clay soil, which accounts for why it has survived for centuries in an area prone to flooding. Monks Mound was enlarged and expanded over time, but eventually damaged in an earthquake in the time preceding the abandonment of the city.
Because the culture at Cahokia did not leave written records or inscription, little information about the purpose of the great mounds has survived. Archaeological evidence from the site suggests the mounds were a key part of the religious practices of the culture.