The South Street Seaport is located in the Southernmost tip of Manhattan. It used to be a busy seaport - hence, the name - and now it's a huge open air museum, with several beautiful ships that you can visit. There's also a museum, dedicated to this area and seafaring in general. It's also a shopping heaven and is also full of restaurants for all kinds of budgets. You can get there easily by subway. Take the #4, 5, or 6 train on the Lexington line and get off at Fulton Street, then, simply follow Fulton Street all the way to the Seaport, due East. You can also take the A train to Broadway-Nassau Street or Fulton Street, or the #2 (IRT line) to Fulton Street. Follow the instructions as above. If you decide to visit Ground Zero (formerly the World Trade Center), follow Fulton Street but to the West. Just keep walking and you'll get there.