 The first light house on the island was completed in 1854, and served the bay during its time as a Citadel and military prison.It was replaced by a taller ( above mean sea level) concrete tower built in 1909 to the south of the original one which was demolished after it was damaged due to earthquake in 1906.The automation of the lighthouse with a modern beacon took place in 1963, the year Alcatraz closed as the Alcatraz Federal Penitentiary.