This is the city's only private park, and though it can feel a bit out of place in an otherwise resolutely democratic city, its aristocratic charm has captivated Manhattanites since 1831, when it was built by entrepreneur and small-scale real estate speculator Samuel Ruggles on top of a marshland, to help attract buyers to his property holdings. The park is modeled after London's many small, elegant squares, and is as exquisitely maintained as any plot in Europe. Only those neighborhood residents whose windows overlook the park (or whose buildings front the park) are provided keys; for all others, peeking through the gorgeous wrought-iron fence will have to suffice.