Earth Vs The Flying Saucers (1956)
Made at the height of the 1950s UFO craze, this B-movie features a by-the-numbers alien invasion plot opposed by an array of cardboard cutout stock characters. But it's the effects – by a young Ray Harryhausen – that have stood the test of time. The titular saucers eerily gliding over Washington DC's monuments remain iconic – and have been homaged in the likes of Mars Attacks! and Independence Day.