Fodor's Expert Review Haus der Musik
You could spend an entire day at this ultra-high-tech museum, housed on several floors of an early-19th-century palace near Schwarzenbergplatz. This is a highly interactive experience; in "Facing Mozart," visitors animate a Mozart portrait using a technology called facetracking. Assuming the role of virtual conductor, you can conduct the Vienna Philharmonic (or a video projection of it, anyway) and have the orchestra follow your every command; the conductor's baton is hooked to a computer, which allows you to have full control over the simulated orchestra. For added fun, the stairs at the beginning of the tour are musical; each step produces a note. Other exhibits trace the evolution of sound (from primitive noises to the music of the classical masters) and illustrate the mechanics of the human ear (you can even measure your own frequency threshold).