Did you know...that Battery Park's Castle Clinton was originally built as a fort to defend New York Harbor from the British in the War of 1812? Additionally, it first stood on an island 200 feet from shore, until a landfill later connected it to the mainland. Designed by John McComb Jr. and Jonathan Williams, the red sandstone, circular fort was never used for military purposes. Instead, it became Castle Garden entertainment center in 1824, and reached its peak in 1850 when it hosted the U.S. debut of Swedish chanteuse Jenny Lind. Since that time, Castle Clinton has functioned as an opera house, an aquarium, and a processing center for more than 8 million immigrants. It was designated a national monument in 1946, and now serves as the ticket center for ferries to Ellis Island and the Statue of Liberty. Inside are dioramas of Lower Manhattan in 1812, 1886, and 1941.