New York Harbor from the Battery (circa 1906) showing Castle Garden
Castle Garden was New York's immigrant processing center from 1855 to 1890. From 1896 to 1941 it was New York City's Aquarium. Today Castle Garden is called Castle Clinton National Monument. It serves as a visitor information center for New York's National Parks and Monuments. You can also purchase tickets there for ferry trips to Ellis Island and the Statue of Liberty.
This picture is from... The Library of Congress, Prints and Photographs Division, Detroit Publishing Company Collection
Finding Castle Garden Passenger Lists
Castle Clinton National Monument Website