Quatermass and the Pit (aka 5 Million Years to Earth)

Ranks with The Devil Rides Out and The Horror of Dracula as one of Hammer Studio's best films. This, however, is a sci-fi film about a mysterious space craft unearthed in the London subways system (you just never know what you'll find down there). At first, prehistoric ape skulls are discovered, invigorating an ambitious scientist. The spaceship is revealed to be inhabited by dead, ancient insect Martians that, like the monolith from 2001: A Space Odyssey, are responsible for initiating the evolution of ape into man. Actually, the idea that our species is a result of telepathic, insectoid Martians could explain a great deal. Nevertheless, this is a strangely intelligent film that doesn't sell itself short. The climax involving a giant ghost insect hovering over the city is one of those images that will probably stick with you.