Oh, how to take your breath away sitting in the dark with just a pin hole of light to bring the world inside like the fragments of a dream. The camera obscura is really one of the most amazing and simpliest inventions ever, yet it can create a truly astonishing effect in a darkened room. Here is a brief description from Open Culture:
"Long before the invention of photographic film, it was discovered that if you have a darkened room with a small hole in it, the light passing through will project an upside-down image of the surrounding scenery onto the opposite wall. The Chinese philosopher Mo Tzu, who died in the early 4th century BCE, called it the “locked treasure room.” In 1604 the German mathematician and astronomer Johannes Kepler coined the term “camera obscura,” or darkened room."
Here is a film of photographer Abelardo Morell demonstrting how he transported an image of Venice, from the outside onto the walls of a room through the lens of a camera obscura.
And here's how to do it...a very nice short instructional video on how to create your own camera obscura.
And stop by Abelardo Morell's website to see more photographs of his experiments with the Camera Obscura -- they are really astonishing.