Castle Clinton, a former defensive fortress turned immigrant processing center from 1847 to 1890, is located in Battery Park, Manhattan. After serving various roles, including as a beer garden and aquarium, it was designated a national historic landmark in 1966. Originally named after De Witt Clinton, the mayor of New York, the fort played a crucial role in welcoming immigrants, especially during the Irish wave caused by the potato famine. In 1890, with the opening of Ellis Island, its service as an immigration center concluded.