Quatermass and the Pit (1967)

Excavation for a new subway in London reveals a mysterious artifact. Reknown scientist Bernard Quatermass (Andrew Keir) is called in to assist in the investigation and identification of what some fear to be a unexploded bomb. Of course, it is something completely different but could be equally earth-shattering, if not more so. Released in the US as FIVE MILLION YEARS TO EARTH, I still find this film entertaining despite its age.