The National Park Service is celebrating the 50th anniversary of the day Alcatraz Island closed as a federal penitentiary with a new photo exhibit and talks by former prison guards.

The event is scheduled to begin at 10 a.m. Thursday.

Alcatraz started as a fort before becoming an Army disciplinary barracks. The Bureau of Prisons took it over in 1934 and housed some of America’s most notorious inmates there, including Al Capone, before closing it down in March 1963.

It later was occupied by American Indians for 18 months. The island became part of the Golden Gate National Recreation Area in 1973 and remains a popular tourist destination.