Over about 300 years, this village developed four ditch fortification systems, with the fourth and outermost ditch probably the oldest. Although no longer visible on the ground surface because of two later village activities, this ditch lay outside most mounds and included several prominent bastions similar to those at Shermer and Huff villages dating to about AD 1350-1460, slightly before the founding of Double Ditch. The earliest houses at Double Ditch were likely rectangular like those at Huff and Shermer, built in shallow pits about one or two feet below the ground surface with gabled roofs supported by three or more main posts along the centerline. In the 1500s, house form shifted from rectangular structures to circular earthlodges. As the village contracted in size, midden mounds were built over parts of Ditch 4. The outermost ditch enclosed about 22 acres, and based on house density at comparable sites from the same period, it probably held 160 homes and perhaps 2,000 residents within the outer fortification system, making Double Ditch larger than at least 95 percent of North Dakota towns and cities today.