Angel Island is an island in San Francisco Bay offering expansive 360° views of the San Francisco skyline, the Marin County Headlands and Mount Tamalpais. The entire island is included within Angel Island State Park and is administered by California State Parks. The island, a California Historical Landmark, has been used for a variety of purposes, including military forts, a US Public Health Service Quarantine Station, and a US Bureau of Immigration inspection and detention facility.