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.
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.
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.
FOR MORE ALCATRAZ INFORMATION
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