This museum has finally found a permanent home, and one within a work of art itself: an eight-story building designed in 2002 by heralded husband-and-wife team Tod Williams and Billie Tsein. The facade, consisting of 63 hand-cast panels of alloyed bronze, reveals individual textures, sizes, and plays of light. Inside, four gallery floors -- dedicated to exhibitions and the collection of arts and decorative objects from the 18th century to the present day -- are naturally lighted through a central skylight. Using multiple paths of circulation, an open atrium, and balconies of clear glass, you are treated to an architectural mix of intimacy and aspiration that echoes the folk art on display. Works include paintings, weather vanes, quilts, pottery, scrimshaw, and folk sculpture such as carousel animals and trade figures. COST: $9; free Fri. 5:30 PM-7:30 PM. Wed.-Thurs. and weekends 10:30 AM-5:30 PM, Fri. 10:30-7:30. Subway: E, V to 5th Ave./53rd St.