When this circular, red sandstone fort was built in 1811 to protect New York City during the War of 1812, it was called West Battery. Four years later, the name was changed to Clinton Castle as a tribute to Mayor DeWitt Clinton. The fortress never saw battle. From 1855 until 1892, this was the main processing center for more than eight million immigrants before the function moved to Ellis Island. Clinton Castle is now a National Monument managed by the National Park Service.