Alcatraz Citadel Alcatraz Citadel , also known as Fort Alcatraz , was the original military defense and prison on Alcatraz Island , off the coast of San Francisco , California , USA . The citadel was built in 1859 as a U . S . Army military defense , and began function as a war camp in 1861 and long - term military prison in 1868 . During the American Civil War , the citadel and its batteries provided an important line of defense . The island continued to develop in the 1870s and 1880s , and in 1893 , the first hospital on Alcatraz opened . A new upper prison was built in 1904 , but after the citadel ceased function as a military defense in 1907 and the original citadel collapsed the following year , a $ 250 , 000 concrete military prison was erected between 1910 and 1912 . In 1933 - 4 , this was modernized and became the Alcatraz Federal Penitentiary . It housed some of America ' s most dangerous criminals between 1934 and 1963 . History . Early history . Native Americans , known as Ohlone ( A Miwok Indian word ) , were the earliest known inhabitants of the Alcatraz island before it attained its niche in history as the most secure prison for notorious criminals . Even though they avoided the island as they believed that evil spirits resided there due to the bad atmosphere they got from the place , they were using it for deporting their criminals under the tribal law to live on the island in isolation . They also gathered eggs of birds and marine food from the island . Even after the Spanish discovered the Island in 1759 , and started spreading Christianity , the natives who did not want to convert used the islands as their refuge . 19th century . However , the earliest recorded owner of the island of Alcatraz is Julian Workman , to whom it was given by Mexican governor Pio Pico in June 1846 , with the understanding that Workman would build a lighthouse on it . Julian Workman is the baptismal name of William Workman , co - owner of Rancho La Puente and personal friend of Pio Pico . Later in 1846 , acting in his capacity as Military Governor of California , John C . Fremont , champion of Manifest Destiny and leader of the Bear Flag Republic , bought the island for $ 5 , 000 in the name of the United States government from Francis Temple . In 1850 , President Millard Fillmore ordered that Alcatraz Island be set aside specifically for military purposes based upon the U . S . acquisition of California from Mexico following the Mexican - American War . Fremont had expected a large compensation for his initiative in purchasing and securing Alcatraz Island for the U . S . government , but the U . S . government later invalidated the sale and paid Fremont nothing . Fremont and his heirs sued for compensation during protracted but unsuccessful legal battles that extended into the 1890s . Following the acquisition of California by the United States as a result of the Treaty of Guadalupe Hidalgo which ended the Mexican - American War ( 1848 ) , and the onset of the California Gold Rush the following year , the U . S . Army began studying the suitability of Alcatraz Island for the positioning of coastal batteries to protect the approaches to San Francisco Bay . In 1853 , under the direction of Zealous B . Tower , the United States Army Corps of Engineers began fortifying the island , work which continued , and the citadel was completed in 1859 , on a budget of $ 87 , 689 . The first step in this direction , taken up in 1853 , was the start of construction of a fortress or citadel at the top of sandstone rock outcrops . The island was encircled with steep walls built of stone and bricks abutting the rock faces , and buildings for accommodating defense personnel and offices and temporary launching jetty were also added . A lighthouse was built and 11 cannons were fixed . The main fortress took many years to build as the building material ( granite ) required for construction had to be imported from China . Army engineer James B . McPherson , later to become a prominent general during the Civil War , was one of the earliest commanders to serve on Alcatraz in 1858 . The three - storied citadel took final shape by 1859 when gun positions , roads , guard houses and draw bridge over the moat ( encircling the citadel ) were all added . The citadel had housing capacity for 200 soldiers with food storage facility to last for four months in case of any long drawn attack . In 1859 , the coastal defense system became a reality and Captain Joseph Stewart was commander of the island forces which included 86 men of Company H , Third U . S . Artillery , before departing from the island in 1861 on the outbreak of the Civil War . The military officers wore blue suits and white gloves . In 1861 , the citadel commenced function as a prison , with tiny new cells being added to the basement , and in 1867 was extended , becoming a long - term military prison in 1868 . The citadel on Alcatraz was crucial to defense during the American Civil War ( 1861 – 1865 ) , having some 111 cannons encircling the island at peak , and was also used as a war camp . During the Civil War , the defense establishment at Alcatraz Citadel had the onerous task to defuse the possibility of any local war between the Union and Confederate supporters who were both part of the population of California , and to protect San Francisco . Ammunition in the form of 10 , 000 muskets and 150 , 000 cartridge s was supplied to the fort , which made the Fort Alcatraz and the island most impregnable and thus leaving any plans of the Confederate soldiers of taking control of the San Francisco Bay and California State could be taken under its fold was thwarted . Alcatraz was officially designated as a military prison on August 27 , 1861 . In March 1863 , when there was a threat that the San Francisco Bay would be captured by the Confederates , the schooner , which was to carry out the operation set sail ; the U . S . Navy prevented the schooner from moving out and captured the crew along with ammunition and 15 confederates who were hiding in the galleys of the ship . Consequent to this , the importance of Alcatraz increased , more and more confederates and civilians were arrested for reasons of treason and kept in the military prison , and to accommodate the increased number of prisoners , a temporary makeshift wooden prison was built in 1863 to the north of the guardhouse . In 1864 , with civil war showing no signs of abating , fortifications were provided in the fort in the form of 15 - inch Rodman cannons and more " bomb - proof barracks ” built . At the time of end of the Civil War in 1865 , there were more than one hundred cannons in the island , which were never put to any aggressive battle , but used only once to provide gun salute in honor of President Abraham Lincoln at his official funeral procession held in San Francisco . As the civil war ended , the military prison housed Confederate sympathizers who celebrated Lincoln ' s death . During the Indian Wars that followed the civil war , Indians who went against the government were sent to the Alcatraz prison . On June 5 , 1873 , Paiute Tom was the first native American who was imprisoned there on transfer from Camp McDermit in Nebraska . In the 1870s , Major George Mendell ordered the prisoners , aided by mules , to assist in changing the natural landscape of the island and creating a top level , dumping debris into the 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 first hospital on Alcatraz opened in 1893 . As the number of prisoners to be housed in the citadel increased , more space was built in the form of the Upper Prison , which consisted of three wooden structures , each of two tiers , with the lower prison getting converted as a workshop . However , both Upper and Lower Prison cells , being made of wood , were frequently subject to fire hazards , and this led to change of the structural form of the barracks ; concrete structures were built , replacing the wooden ones . 20th century . In 1904 , an upper prison building was built at a higher level on the island and replaced the lower prison , with a capacity of 307 inmates . Alcatraz was renamed as the " Pacific Branch , U . S . Military Prison ” in 1907 , and as the importance of the Island citadel became less and less obvious due to modernization of the naval facilities , infantry soldiers were shifted and prison guards brought in their place . It developed a reputation for its brutal methods of torturing prisoners , placing prisoners in pitch black cells for up two weeks . Alcatraz was barely affected by the 1906 San Francisco earthquake which devastated the city , and the prison population dramatically increased as prisoners were temporarily transferred to the island due to damage in the city . In 1907 , Alcatraz Citadel ceased function as a military defense and became the Pacific Branch , U . S . Military Prison solely . When the original 1860s citadel collapsed in 1908 , the Citadel was demolished in 1909 up to its basement over which the new prison was built by the military prisoners between 1909 and 1911 and named as “ the Pacific Branch , U . S . Disciplinary Barracks for the U . S . Army ” , which became popular as " The Rock " . The prison was entirely rebuilt in concrete in 1910 - 1912 under the command of Colonel Reuben Turner on a $ 250 , 000 budget on the site of the remains and short - lived upper prison building . Many of the former underground tunnels and chambers of the original fort remain today and are still accessible . This building was modernized in 1934 when it reopened as a federal penitentiary , the notorious Alcatraz prison which held America ' s most ruthless criminals until 1963 . During the World War I , the citadel was used for incarcerating military prisoners as also German Prisoners of War , which necessitated building of a larger building structure by demolishing the old upper and lower prisons . A new cell house formed of four cell blocks with 600 cells was built , in 1912 , which at that time was reported to be the largest reinforced concrete building in the world ; the cells had toilet and electricity facilities . In the new established order , facilities for education and rehabilitation of prisoners with minimum offence were also introduced which resulted in many reformed prisoners getting back to the army . Even though the prison was a military establishment , it had its fair share of prison escapes . 29 escapes were reported involving 80 convicts out of which 62 were caught and tried while the rest of the prisoners were not traced . In the prison escape of November 28 , 1918 , there were four prisoners who escaped in rafts , and they were seen at Sutro Forest . However , only one was caught and the others escaped . Due to high costs of maintenance of the Alcatraz as a defense establishment , a well thought out plan was mooted to convert it into the Alcatraz Federal Penitentiary . Also during this period crime rate had escalated in the country due to the great depression with prohibition further exacerbating the situation resulting in mobsters and gangsters operating freely indulging in looting , violence and killings , with the law enforcing agencies failing to cope with the situation ; prison escapes had become the order of the day . The suggestion to convert the Military Prison into a Federal Penitentiary was welcomed by the President Herbert Hoover and thus the maximum - security prison was created . The proposal for transfer of Alcatraz to the Bureau of Prisons was initiated in October 1933 and after a vigorous adaption from the military prison throughout 1934 , it opened in August 1934 , ending some eighty years of U . S . Army occupation . With this change of guard , 32 hardcore prisoners remained at Alcatraz while the rest were shifted to the prisons at Fort Leavenworth , Kansas , United States Penitentiary , Atlanta , Fort Jay , New Jersey and several others . Architecture and fittings . The main mode of transport accessing the island was the " General McPherson " . Upon embarking at the port , the main grounds would be reached by a " long dreary corridor " known as the sally port and a drawbridge surrounded by a dry moat , below . It could hold up to 200 men during an emergency and enough supplies to last four months . Alcatraz Citadel consisted of a basement , which contained the kitchen , bakery , bedrooms , storerooms and jail cells , and two levels above ground which contained the military personnel quarters , servant quarters , parlors and a mess room . In - ground water tanks and water tanks were situated on the roof of the citadel . Other buildings included the Batteries of Rosecranz and Halleck in the north , the barracks building in the northeast , the Battery of McClellan and Fog Bell House in the south , the Battery of McPherson in the west and the Batteries of Stevens and Mansfield in the northwest and the lighthouse aside the main citadel . Battery McClellan was equipped with a 15 - inch Rodman gun weighing over 25 tons , capable of launching a 330 pound explosive 4 , 680 yards when angled at 25 degrees . The Parade Grounds were located in the left centre . When the new concrete prison was built in 1910 - 2 , iron staircases in the interior were retained from the old citadel and massive granite blocks originally used as gun mounts were reused as the wharf ' s bulkheads and retaining walls .