Alcatraz islands off the cost of San-Francisco have only two lighthouses. The foundation of the first was laid in 1852, and the entire structure became operational in 1854.
The first lighthouse was a two storey structure with a tower at the center. The fifty-foot structure was black and white and used a fixed third order lens. The need for this lighthouse can be attributed to the 1849 gold rush, which made west coast lighthouses a priority. By 1856, it was found that the San-Francisco fog often rendered the lighthouse ineffective. This led to the installation of a fog-bell. The bell was first rung by hand and later, thanks to a clockwork mechanism, the bell would ring automatically at prescribed intervals. Due to the growth of the city, a flashing fourth order lens had to be installed later, to help mariners distinguish the lighthouse from the city lights. This lighthouse was badly damaged in the 1906 San-Francisco earthquake, which cracked the lighthouse tower and toppled one of its chimneys.
The military prison on the island rendered the old lighthouse ineffective and by 1909, work started on a new lighthouse. With an eighty four feet tall tower and fog sirens at the front and back of the island, the new light house ran on electricity. In 1963, when the Alcatraz prison was finally closed due to the high maintenance cost, the lighthouse was automated.
The lighthouse stopped working for a short while in 1969, when electricity to the island was cut because it was being occupied by the natives. Power was restored after a while, with the help of a generator smuggled in by prominent San-Francisco citizens who were worried about maritime safety.
By 1972, the natives were driven out and Alcatraz became a national reserve. Today a 200,000 candle power lens is used in the old lighthouse.