Like a set from a sci-fi movie, a monumental concrete-and-glass sphere—150 feet in diameter and appearing simultaneously weighty and buoyant—hovers beside the main wing of L.A.’s new Academy Museum of Motion Pictures (AMMP). It’s clearly no ordinary building addition. And on that fanciful note, architect Renzo Piano sets the scene for this homage to Hollywood’s movie industry—its on-screen and backstage artistry and technological feats—from vintage through cutting-edge.