Stand inside Castle Clinton, and you can imagine manning the cannons that once pointed through its massive stonewalls. Built in 1811 as a fortress against invaders, the Castle has undergone surprising and sometimes shocking transformations over the past two centuries.

In 1824, the once proud fort became a restaurant and entertainment venue called Castle Garden. Later, after the addition of a new roof, it was transformed into an opera house, theater and site of the first demonstration of Samuel Morse's telegraph. A generation later, the structure resumed an official role, this time as America's first immigration center. Over the course of 34 years, 8 million people entered the United States there until the duties were transferred to newly built Ellis Island. Almost immediately, its schizophrenic reincarnation continued when the building reopened as the New York City Aquarium on December 10, 1896! It remained one of the city's most popular attractions until closing during World War II. As you stand within its storied walls, you can ponder this impossibly rich history as you wait to purchase tickets for Ellis Island and the Statue of Liberty.