Why was alcratrz built?

Alcatraz was originally built as a military fortification in the 1850s, designed to protect San Francisco Bay from potential naval attacks during the California Gold Rush. Later, it was repurposed as a federal prison in 1934, intended to house the most dangerous criminals and prevent escape attempts due to its isolated location on an island. The prison gained notoriety for its harsh conditions and high-profile inmates, further solidifying its place in American history.