Unlocks the Builder ability to construct a Cahokia Mounds.
+3 Gold, +1 Housing. Cities with Cahokia Mounds receive +1 Amenity, extra +1 for cities with at least 2 Cahokia Mounds. +1 Food for every adjacent District, which becomes +2 Food after progressing 'Historical Philosophy' Civic. Cannot be built adjacent to another Cahokia Mounds.