Tour the historic Riley farm where Rev. Josiah Henson was enslaved from 1795 to 1830. Henson’s 1849 autobiography inspired Harriet Beecher Stowe's landmark novel, Uncle Tom's Cabin. Explore an archaeology dig; make your own set of marbles. Tours on the half hour, noon-3pm. Park at the Kennedy Shriver Aquatic Center, 5900 Executive Blvd.