While we're on the subject of New York City, if you've never been to the New York Botanical Garden in the Bronx, you're missed one of the prettiest and most interesting natural places in the city. There are more than 250 acres of beautifully landscaped acres that look more like a wooded landscape in Vermont than they do a Bronx park. In fact, just strolling through the wooded hills and exploring the many "hidden" gardens is a wonderful way to spend an afternoon. But the gem of the garden, of course, is the very impressive Enid A. Haupt Conservatory (pictured here)--a flamboyant Victorian-style greenhouse that provides a beautiful tropical escape in any season.
There's not a lot of light in the conservatory because of the dense plantings, so you may have to turn up the ISO a bit or pop on the flash (which is allowed). Also, while I wasn't as impressed with the plantings I saw (there are rotating shows in the main conservatory) as I have been with the indoor gardens at Longwood Gardens, it's still quite an impressive collection and a very pleasant place to spend a few hours.
There is also a nice cafe and a gift shop. The gardens are an easy 20-minute train and a short walk from Grand Central Terminal. Hours, fees and directions are listed here. (Photo Copyright 2008 Jeff Wignall, all rights reserved.)