Tom Roston

Just a BlackBerry's throw from Wall Street, architect and designer David Rockwell has designed a space where the 12-and-under set can be the masters of their own universe. The man known for creating immersive environments for adults (L.A.'s Kodak Theatre, the Nobu restaurants) is debuting his first complex for kids—the $7.4 million Imagination Playground at South Street Seaport. The Tribeca dad of two (son Sam is 10 and daughter Lola, 8) helped design the temporary Ground Zero viewing platform in 2002, and was eager to contribute more to downtown's future. He's tapped the European tradition of adventure playgrounds, in which creative fun is prioritized over the exercise of gross-motor skills. "Play is how we explore the world," he says. "And so many great playground ideas have been edited out by overplanning." The space's perimeter is a wooden runway in the shape of an infinity symbol (or, according to Lola, a peanut). The area within is dominated by loose parts—mostly found objects, such as wheelbarrows, buckets, rope and large white sheets—and a truckload of foamy blue shapes manufactured by Rockwell's design team. There is also an abundance of sand and water. Bring all that under the direction of a six-year-old, and Imagination Playground promises to be an adventure of Rube Goldberg proportions. Although there will always be Parks Department--trained "play associates" on hand to oversee the loose parts, things are bound to get messy—which is a good thing, according to Rock

Best place to (legally) jump a turnstileThe New York Transit Museum Strange but true: There's a place that makes the MTA seem like a source of goodness, magic and whimsy. The Museum's simulated traffic intersection (replete with traffic lights and DON'T WALK signs) cleverly brings the city down to kid-scale, just as every child dreams it should be. Tots can interact with different generations of turnstiles and subway cars, gawk at tokens and play at driving a real, decommissioned bus. As for parents: Marvel as your own cynicism evaporates. Boerum Pl at Schermerhorn St, Downtown Brooklyn (718-694-1600, mta.info/mta/museum) Best unsung ediblesGratis pickles, cole slaw and pickled beets at Junior's The cheesecake is the restaurant's claim to fame, but we like to work our way up to the sweet slab of loveliness. There's no better way to begin than with the perfectly salty-sour pickles and other crunchy bites that are served before every meal at Junior's. The jury's out on whether nutritional value is lost in the pickling process, but we're guessing your kids won't mind either way. 386 Flatbush Ave at DeKalb Ave, Downtown Brooklyn (718-852-5257, juniorscheesecake.com) Best place to study the physics of waterThe fountain in front of the Brooklyn Museum The dancing display was designed by the same folks who created the fountain at Las Vegas's Bellagio. On some days, the spouting jets can entrance children into a quiet bliss, as they watch the rhythmic crescendo of water and light. On