This piece of guerrilla art appeared under the train trestle at Encinitas Blvd and Hwy 101 in the city of Encinitas. The artist or team of artist are currently unknown. Mistaken as a painted mural at first glance the piece is actually a very intricate mosaic.
The city of Encinitas will most likely remove it before too long so if you are in the area stop and take a look.
Story and second photo from the San Diego Union Tribune
Other photos from Fred Caldwell, the Taped Off Blog and the Leucadia Blog.