NYU's "campus" is New York City. Its heart is in Greenwich Village around Washington Square Park with important hubs along the Health Corridor of First Avenue near 30th Street, near Midtown East, and in downtown Brooklyn. With institutes, centers, and academic buildings reaching as far north as the Upper East Side, and as far south as the Financial District, getting from place to place at NYU requires a little assistance.
Luckily, there are a lot of options available to get around New York City. University Transportation services run between all of the major academic building locations, including the Medical Center, and NYU residence halls.
The MTA (Metropolitan Transportation Authority) runs the subway, train and bus systems that will also get you where you need to go.
If all else fails and you're in the Village, head over to Broadway to catch a cab downtown or over to Sixth Avenue to catch one going uptown.