North Waterfront in San Francisco City and County, California — The American West (Pacific Coastal)

Main Prison Building

Photographed By Joseph Alvarado

1. Main Prison Building Marker

Inscription. In 1907, the War Department drew up plans for a new prison building that could house up to 600 Army prisoners. When finished in 1912, the cellhouse was reportedly the largest steel-reinforced concrete building in the world.

Unskilled Army inmates largely provided the labor. When Alcatraz was chosen as a federal maximum-security penitentiary in 1934, the aging cellhouse was renovated by the Bureau of Prisons. Tool-proof bars replaced the flat, mild=steel cell fronts of the military prison, and gun galleries were built at either end of the cell room. Also, the number of cells was reduced from 600 to 336.

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[#11-Main Prison Building]

(Marker Number 11.)

Topics. This historical marker is listed in these topic lists: Forts and Castles • Law Enforcement • Parks & Recreational Areas. A significant historical year for this entry is 1907.

Location. 37° 48.39′ N, 122° 24.263′ W. Marker is in San Francisco, California, in San Francisco City and County. It is in North Waterfront. Marker can be reached from The Embarcadero south of Bay Street, on the right

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when traveling north. The resin marker is mounted to a 3-D topographical map of Alcatraz Island. Touch for map. Marker is at or near this postal address: Pier 33, San Francisco CA 94133, United States of America. Touch for directions.

Other nearby markers. At least 8 other markers are within walking distance of this marker. Warden’s House and Lighthouse (here, next to this marker); The Dock (here, next to this marker); The Post Exchange & Officers' Club (here, next to this marker); Industrial Buildings (here, next to this marker); Guardhouse & Sallyport Complex (here, next to this marker); Staff Housing Area (here, next to this marker); Military Schoolhouse (here, next to this marker); Barracks/Apartments (here, next to this marker). Touch for a list and map of all markers in San Francisco.

More about this marker. There is a small braille plaque on the lower left corner of the marker.
Inset Images:
The penitentiary cellblocks contained one man cells.
Inmates and correctional officers bundled up against the cold in the recreation yard.
Convicts were allowed yard privileges on weekends.
Alcatraz correctional officers, 1934. Warden James Johnston at center.

Also see . . . Alcatraz Cellhouse. National Park Service

"D-Block housed the worst inmates in solitary confinement."

(Submitted on July 18, 2023, by Joseph Alvarado of Livermore, California.)

Main Prison Building Marker and Topographical Map image. Click for full size.

Photographed By Joseph Alvarado, June 15, 2023

2. Main Prison Building Marker and Topographical Map

Marker on the right-center.

Credits. This page was last revised on July 18, 2023. It was originally submitted on July 18, 2023, by Joseph Alvarado of Livermore, California. This page has been viewed 55 times since then and 15 times this year. Photos: 1, 2. submitted on July 18, 2023, by Joseph Alvarado of Livermore, California.

Editor’s want-list for this marker. Photo of the cellhouse. • Can you help?