Alcatraz Federal Penitentiary and the island became a prison of the Federal Bureau of Prisons in August 1934 after the buildings were modernized to meet the requirements of a top-notch security prison. Given this high security and the location of Alcatraz in the cold waters and strong currents of San Francisco Bay, the prison operators believed Alcatraz to be escape-proof and America's strongest prison. Alcatraz was designed to hold prisoners who continuously caused trouble at other federal prisons. One of the world's most notorious and best known prisons over the years, Alcatraz housed some 1,576 of America's most ruthless criminals including Al Capone,
Alcatraz Citadel coves and bay. In 1882, the citadel was enlarged to provide more accommodation for the families of the military officers working on Alcatraz. Between 1873 and 1895, 32 Native Americans were imprisoned at the citadel on Alcatraz, including 19 Hopi men held in captivity there between January and August 1895 after being transferred from Fort Defiance. The island continued to develop in the 1880s and in 1898 the population of Alcatraz increased dramatically from 26 to over 450 due to the Spanish–American War and placed a demand for new buildings. The original barracks evolved into Building 64 in 1905. The