The Bronx Botanical Garden is a place my father and I have been going to since I was a child. Here's a photograph I took of him here. It has hundreds of species of trees and flowers. Sitting in the middle of the Bronx, it's most recognizable as a green oasis from the grays and concrete of city life.
This Bookstore has an amazing photography section. I go here to get inspired. You can spend hours in here looking at all kinds of great photography books.
Webster Hall is a solid venue, and a frequent stop for many great bands on their rise to glory. If you've only got a few nights in the city, chances are a great act will be playing here.