Main Prison

Prisão Principal is a concrete and steel structure on Alcatraz Island designed with thick walls, reinforced doors, and guard towers positioned around its perimeter. The building layout includes cellblocks, a dining hall, a library, and administrative areas that worked together to manage inmates under strict control.

The facility opened in 1910 and operated as a federal penitentiary until it closed in 1963. Over that period, it housed some of the nation's most dangerous offenders in strict isolation from the mainland.

The name reflects its role as a maximum-security federal penitentiary in the United States. Visitors today can observe the cells and experience how inmates lived within these confines.

Access is only by ferry from Pier 33, and audio guides in multiple languages are available to explore the facility at your own pace. Good walking shoes are recommended since the site involves climbing stairs and navigating uneven terrain throughout.

The prison kitchen served high-quality meals to prevent unrest and used metal utensils despite security concerns, relying on the island's isolation to make escape nearly impossible. This unusual approach to feeding inmates revealed how geography itself was part of the security system.

Location: San Francisco

Address: San Francisco, CA 94133, USA

Phone: +14155614900

Website: https://nps.gov/alca

GPS coordinates: 37.82663,-122.42293

Latest update: December 12, 2025 03:23