Today is the 52nd anniversary of the closing of the Alcatraz federal prison in San Francisco Bay.

Here are a few things you might not know about Alcatraz:

• It was open for only 29 years. It opened in 1934 and closed in 1964. The closure was because of the high cost of operation and deteriorating facilities due to the salt air.

• The Birdman of Alcatraz never kept birds at Alcatraz. Robert Stroud, a convicted murderer, became a self-taught ornithologist while in prison in Leavenworth, Kansas, but was not allowed to have birds at Alcatraz.

• The 1962 escape attempt by three prisoners was one of the main reasons cited for closing the prison. The prisoners were never found, and were presumed to have drowned by prison officials.