A main curtain that challenges the Chrysler Building in Art Deco beauty. Four luggage-tossing, red-capped porters who tap dance and sing their way across the stage. Then the big reveal of the huge 20th Century Limited train itself—blue-gray metallic, slanted out toward the audience under the black iron and glass ceiling. Surely this set, which appears only once in the show, is the most magnificent Broadway has seen in years.