The Pontiac Silverdome was a stadium in Pontiac, Michigan. It opened in 1975 and sat on 199 acres (51 ha) of land. When the stadium opened, it featured a fiberglass fabric roof held up by air pressure, the first use of the architectural technique in a major athletic facility. With a seating capacity of 82,666+, it was the largest stadium in the National Football League (NFL) until FedExField in Landover, Maryland, a suburb of Washington, D.C. Wikipedia