German film titan Fritz Lang made "Metropolis," a sci-fi film whose groundbreaking design and social message are still influential. He only returned to the genre once for the more realistic "Woman in the Moon." The early parts have something of an espionage/crime bent that will be familiar to viewers of his "Mabuse" films, while the second half takes place on the moon. He strove for realism and was actually advised by scientists, but the moon has breathable air, Earth-like gravity, sand on the surface and bubbling pools. At close to 3 hours, it runs a little long and is slow in parts, but it's a must for fans of Lang and German silent films.