If you go into a room darkened by a heavy shade on a sunny day and prick the shade with a pin, you will see the image of the outside world on the opposite wall, in color but upside down. This dark room, or camera obscura in Latin, illustrates the physics and origin of the modern photographic camera.

This phenomenon was observed as early as the 5th century BCE in China and was studied by Aristotle, the Arabian scholar Alhazen of Basra, and Leonardo da Vinci among others, particularly as a technique for viewing solar eclipses.

The complexity of the camera obscura remained at the level of a pin prick in a darkened tent until the 16th century when lenses and mirrors were introduced.

In the early 17th century, the German astronomer Johannes Kepler was the first to use the term camera obscura.

San Francisco's camera obscura, located above the Pacific Ocean behind the Cliff House, was built by Floyd Jennings in 1946 as an attraction for nearby Playland-at-the-Beach. About ten years later, Mr. Jennings modified the building to look like a camera carelessly left behind by a giant tourist enraptured by the view.

The simple mechanism consists of a ten-inch rotating mirror which projects a flowing image of the outside world through focusing lenses onto a horizontal viewing surface.

Cameras obscuras were popular tourist attractions at seaside and scenic locations in the 19th and early 20th centuries. They were also popular for their educational qualities.

There have been at least three cameras obscuras in San Francisco. The first was at Woodward's Gardens. The second Cliff House also contained a camera obscura which was destroyed in the fire that burned the Cliff House in 1907. The camera obscura built by Floyd Jennings in 1946 was the second one to be placed at the Cliff House site, a testament to the enduring fascination of the public with the scenic beauty of this spot.

This camera obscura is one of only two such optical instruments in California. The other is in Santa Monica and was moved in 1955 from its original location near the Santa Monica Pier to the Senior Recreational Center in Santa Monica.

The camera obscura in San Francisco appears to be the last example of a camera obscura in the United States that is contained in a free standing building and is older than fifty years of age.

Other extant cameras obscuras in the United States are less than fifty years old or, if more than fifty years old, have been moved from their original location.

Adapted from NRHP Nomination Form