Cockatoo Island is the largest island in Sydney Harbour. From 1839 it was a penal establishment with prison barracks, a military guardhouse and official residences built by convicts. The island was used for ship repair and shipbuilding activities after the first dry dock was completed by convicts in 1857. It became Australia's biggest shipbuilding and dockyard facility in the 20th century until maritime industrial activity ceased in 1992. These days, Cockatoo Island is a tourist attraction and a cultural events venue for art exhibitions and music festivals.