Rehabilitation of the Alcatraz Guardhouse

men on scaffolding around building
This photo of the Alcatraz Guardhouse was taken during the early stages of the rehabilitation project. To access all of the building, workers first started the project by constructing scaffolding. In this photo, the boathouse (at center right) has not yet been removed, the roofs haven't been repaired and the historic brick has not yet been restored.


History of the Alcatraz Guardhouse

The Guardhouse, one of the oldest and most significant structures on Alcatraz Island, housed the island's very first military prison. Shortly after California became a state, the U.S. Army took possession of Alcatraz and quickly recognized that the island's rocky cliffs and nearly inaccessible shoreline offered excellent defensive features. The army constructed a ring of gun batteries circling the island and in 1857, the army built the Guardhouse with a "sally port," which is a secured, controlled entryway to the fort.
Very shortly after the first garrison arrived on the island, the army needed a place to detain the occasional disorderly solder. The army chose the Guardhouse's secure basement as a military jail cell. The military considered the Alcatraz Guardhouse's basement so secure that over time, other posts began to send their troublesome prisoners to the island for detention. During the Civil War, the army held Confederate spies and instigators in the basement. As the needs of the army and its garrison changed, the army made several, and often complicated, additions to both the top and the side of the Guardhouse. The first addition included a brick chapel and library building to the south of the original Guardhouse; a later addition was a concrete schoolhouse construction on the upper level of the Guardhouse. The army's last addition to the Guardhouse complex was a wooden boathouse, constructed in 1920 at the building's east side that completely blocked off the Guardhouse's original 1857 south elevation and partially blocked the library's arched east elevation.
view of historic buildings on island
Alcatraz Island, circa 1880s


Rehabilitation Work on the Building

Complicated Worksite & Schedule

All construction work on Alcatraz Island is especially complicated because the NPS, its partners, and contractors, all have to ferry over building supplies and ship over their own water source to the island. The Guardhouse construction work was especially challenging because all of the island's daily visitors had to travel safely through the actual construction site. NPS coordinated the delivery of the building materials around visitor arrival and departure times and the work was scheduled around the breeding seasons of the island's bird population.

Rehabilitation Priorities

One of the National Park Service's top rehabilitation priorities was to seismically strengthen the building. The island's main road, that provides visitors and vehicles with access from the dock up to the top of the island, runs directly through the Guardhouse complex. The National Park reinforced the masonry structure to ensure everyone's safety and to keep all visitor circulation patterns open and safe. Workers rehabilitated the building's doors and windows; conducted concrete and brick repair; replaced in kind an exterior wooden staircase to the library attic; and replaced two roofs with new clay tile and fiber cement corrugated panels. Certified hazardous material contractors removed the building's unsafe lead paint and repainted the building with environmentally friendly paint that would stand up to the harsh marine environment. The NPS rehabilitated special historic guardhouse features, including the defensive dry moat, the cannon port "embrasure" and the lower prison room. The 1920s boathouse addition was removed so that visitors could better understand and experience the 1857 Guardhouse and sally port entranceway as it was originally constructed.
covered walkway with ceiling
IN 2013, VIEW LOOKING NORTH, BEFORE BUILDING REHABILITATION: Since the 1920s, the 1850s Guardhouse & Sallyport walkway has been enclosed by the boathouse addition on the right-hand side. (photo circa 2013.)


view of walkway with open arches looking to ocean
IN 2015, VIEW LOOKING NORTH, AFTER BUILDING REHABILITATION: With the removal of the boathouse addition, visitors can now experience the guardhouse's original walkway, with views of Angel Island and the East Bay through its arched openings. The rehabilitation also opened up the army's original  "Alcatrace Island, 1857" sign over the arched sallyport entrance. 


man on ladder working on brick wall
After the wooden boathouse addition was removed, NPS contractors patched, repointed and fixed the brick walls of the 1870 brick library addition.


men with hard hats working inside cramped brick wall
Contractors inserted steel cross beams adjacent to  the historic brick walls to structurally strengthen the walls in the event of an earthquake.


man working at construction table
A skilled carpenter carefully restored the building's original historic windows.


large building with new red clay tiles
Alcatraz buildings deteriorate especially quickly in the marine air. To protect the building, NPS repaired the roofs by laying down new weatherproof material and new red clay tiles, chosen to look similar to the original historic roofing tiles. 
tall white building with open passageway
2015, AFTER REHABILITATION: Viewing looking north towards the guardhouse.


large white building clustered on hill over water
2105, AFTER REHABILITIATION: View of  rehabilitated guardhouse from the water.
people walking through tall white building with red roof
2015, AFTER REHABILITATION: View of guardhouse, looking south towards the dock. Notice the repaired windows and new red clay roof tiles.

The Park has many Alcatraz Island documents that provide more in-depth information about the island's historic buildings and cultural landscapes. To read or download these documents, please visit the Golden Gate National Recreation Area's Cultural Resource Publication page(scroll down to the Alcatraz documents.)

To learn about other interesting Alcatraz rehabilitation projects, please visit the Alcatraz Preservation page. To learn about the stories of Alcatraz, visit the History and Culture page.

Last updated: August 28, 2019

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