Mysterious tiny doors appearing around San Francisco

San Francisco artist Jeff Waldman recently installed the first of twenty tiny doors that will soon uncannily adorn the streets of San Francisco. His description of the project:

The idea is to install small doors, unexplained portals, throughout the city. To start, in San Francisco. These doors would be scaled down to a size that is cognitively possible but whimsically improbable. Tiny ones. Like, Alice Through The Looking Glass, maybe 15-25 inches or so. I don't imagine them to be operable, but the more detailed in appearance the better.

You can read more here. (Via LaughingSquid.)