Time Out says
For one night only, New York families will have four hours to explore 15 lower-Manhattan museums for free! You could participate in events held by venues like The South Street Seaport (live printing press demos!) or the China Institute (ice cream and calligraphy demos)! Maybe you'll even discover an old relative at the National Archives. Make sure to pick up your museum passport at any one of the participating institutions before roaming. All ages.