my visit to Angel mounds Evansville,indiana 2010...Beginning after 1000 CE, people of the Mississippian culture built a town at this site, covering 100 acres (0.40 km2) and situated on a large, terraced mound near the river. Today, Angel Mounds State Historic Site is nationally recognized as one of the best-preserved prehistoric Native American sites in the United States..the town was surrounded by a stockade, with the Ohio River acting as a barrier on the south side. A gateway was placed to the east, about a fourth of the way around from where the eastern flank of the stockade meets the river. A second barrier, a type of picket fence, was set 14 feet outside the stockade. It was designed to slow the attackers as they came into range.