1950s underground city in Wiltshire built for the British government to survive nuclear war. 35 acres, 60 miles of roads. Decommissioned in 2004.
From Wikipedia
Burlington is a city in, and county seat of, Chittenden County, Vermont, United States. It is located 45 miles (72 km) south of the Canada–United States border and 95 miles (153 km) south of Montreal. As of the 2020 United States census, the population was 44,743. It is the most populous city in Vermont.