Fireworks, mummers, games, food, ferry rides, and a tour of an infamous civil war prison. Tomorrow is Delaware City Day, and you can experience all of the above.
The image above was taken for a 1964 survey for the historic building register, and is from the Library of Congress.
The Fort has been fixed up some since then.
I've seen their fireworks show before, and it was definitely worth watching. If you go, have a good time.