The Pontiac Silverdome was a multi-purpose stadium in Pontiac, Michigan, United States. It opened in 1975 and sat on 199 acres (51 ha) of land. When the stadium opened, it featured a fiberglass fabric roof coated in Teflon and held up by air pressure, the first use of the architectural technique in a major athletic facility. With a seating capacity of over 82,600, it was the largest National Football League (NFL) stadium until 2000.