The Pontiac Silverdome was the former home of the Detroit Lions. The stadium, built in 1975, pioneered a new type of stadium ceiling: domed fiberglass held up by air pressure. In its 31 years of operation it hosted football, soccer, basketball, and ultimate frisbee games, concerts, WrestleMania, and even a mass by Pope John Paul II. It closed after the Lions left for Ford Field and has been deteriorating ever since.
When it opened in 1975 with a seating capacity of over 80,000, the Silverdome was the largest stadium in the NFL. Today it is a ghostly sight in its ruinous state. The stadium was sold in 2009 to buyers who had no plans for it. It briefly reopened for a few sporting events, then closed again; subsequently, it was announced the stadium would be auctioning off its property. Some equipment was sold, but most of the stadium was left to decay.
As for the famous silver dome, it collapsed in 2014 and now lies in tatters across the stadium. Exposed to the elements, moss began to grow on the cement floors. There are no plans to repurpose the stadium, but its demolition has been stalled since 2015. Not much is left inside the derelict Silverdome. It’s currently a popular site for urban exploration, but hopefully soon will make way for new growth in the city of Pontiac.
Update December 2017: Demolition has begun—though they had a little trouble at first.