For two weeks, the only Hudson River barge still afloat (it's on the National Register of Historic Places to boot) will be docked at Tribeca's Pier 25 and open to visitors free of charge. Kids will love checking out the barge models, bells and artifacts on display—not to mention George Rhoads's crazy audio-kinetic ball-machine sculpture. They'll learn how goods were transported before the arrival of bridges and tunnels, and also how the city's waterfront lost its importance once the container trucking industry took over. Captain David Sharp leads tours of the barge at 2 and 4pm on weekends, and on May 5, the folk band Mela will play original tunes at 1 and 3pm. Free; donations appreciated. All ages.