The Pontiac Silverdome, formerly known as the Silverdome, is a stadium in Pontiac, Michigan, United States. It opened in 1975 and sits on 127 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 technique in a major athletic facility. The roof has since been removed. With a seating capacity of 82,000, it was the largest stadium in the National Football League (NFL) until FedEx Field (91,000 capacity) in suburban Washington, D.C., opened in 1997.