Statue of Liberty National Monument - http://www.nps.gov/stli
Lady Liberty, perhaps one of the five most recognizable icons in the world. As near as I could discern on an admittedly rushed visit - we were warned the tour of the monument itself would take no less than 30, if not 45 minutes, and crazy nuts that we were, we did it in 20 - I didn't see anything else that was more likely to be THE park sign, other than this brick wall that greets visitors arriving via the two Circle Line ferry boats that come from Battery Park, Manhattan and Jersey City, New Jersey.
More photos of Lady Liberty will be posted at http://upload.pbase.com/ambadale/aj15