The most buzzed-about playground opening in recent memory was this downtown kid hub designed by architect-dad David Rockwell. Eschewing standard playground design, Rockwell instead hands kids the building blocks (some literal) for their own fun: blue foam shapes that fit together every which way, spurting sprinklers and barrels with hoses they can cool down with, and park helpers there at the ready to facilitate mini builders’ grand plans. (Rockwell got the idea from his kids, who, when he brought them home an art table, gravitated toward the foam and box it came in over the gift itself.) Its whimsical seaside-themed elements, like a semicircular boardwalk and mastlike poles in the sandbox, make it fit right in with its seaport surroundings.