When you've lived in Boulder as many years as I have, this city's lack of diversity becomes something of which you (optimally) remain intellectually aware, but isn't something you notice, per se, on any given day. New York is like the reciprocal of that. Pick an ethnicity, race, color of skin--it's not just that people of that category are present, not just that they abound, but that there are enough of them that, somewhere in the city, there's a neighborhood that celebrates their ethnicity. (This is beautiful, of course.)
We've all heard of Chinatown, Koreatown, Little Italy. But there are lesser-known enclaves as well. In south Brooklyn, there's the Lesser Pyramids, where you can get great Egyptian food and, for the right price, have your departed loved ones mummified. Many consider Staten Island's España Pequeña a must-see, especially during the summer bullfight season. Memphis II, built around the questionable assertion that west Tennesseans are their own race, features terrific barbecue and an exact replica of Graceland, no more and no less tasteless than the original. The French Quarter is actually in New Orleans, but knowledgeable people know the exact abandoned phone booths that will instantaneously transport you there.
Don't be fooled into going to Little Tony, though. That's just what Big Tony calls his fifth-floor Murray Hill walk-up. Big Tony is pretty creepy. He'll probably try to touch you.