6. Castle Garden Was Formerly Home to New York’s First Municipal Aquarium

In 1896, Castle Garden reopened as New York’s first municipal aquarium, described by an 1897 Frank Leslie’s Sunday Magazine article as a 20,000-square-foot building with “graceful archways”, a glass-paned roof, and tanks surrounded by plants and shrubs where “his majesty, the whale, swims and blows as only whales can; a rookery for the sea-lion, and a pond for the seals, complete the central view.”

To make sure the structure was suited to house an aquarium, architects McKim, Mead & White had to alter it again prior to its opening. The oldest continually operating aquarium in the United States, it eventually became one of the city’s most popular attractions, bringing in 5,000 guests per day (and 2.5 million visitors a year) thanks to 150 housed specimens, exotic fish and beluga whale that lived there. However, when the attraction shut down in 1941, the fish were temporarily relocated to the Bronx Zoo, and the New York City Aquarium itself was relocated to Coney Island.

In the show The Alienist, Castle Clinton becomes a key plot point, and the monument is shown as it is under construction to become the aquarium.