The Cabinet of Dr. Caligari is said to be the first Horror film ever made, dating back to 1920. Besides this interesting fact, it's full of beautiful and spooky German expressionistic elements in its design and cinematography.
It's also been said that this film introduced the idea of a 'twist' ending... pretty revolutionary for early cinema.
When it comes to German expressionism, it's all about shadows, shapes... and the dark side. Pretty much any film that uses the techniques of German expressionism is a film involving suspense and horror.
The style of this film is purely dark with a fantasy-like look that creates an atmosphere all its own. The Cabinet of Dr. Caligari has got the ultimate look and story that truly makes it the first of its kind.
Here's the full movie from YouTube:
Random Trivia: In 2005, the film was remade with new actors (of course) but not a new set... they decided to superimpose the actors onto the original backgrounds and sets from the original film. All the filming was therefore done on a green screen. Take a look at how they made the 2005 version in these two clips from the DVD... Part One & Part Two.
And PS, guess who plays Cesare, the somnambulist who can predict the future... Doug Jones, the same talented actor who Billy Butcherson in Hocus Pocus!