Well, it's not exactly my Utopia, since I don't see any cars in there, but still, artist Mona Caron did quite a fine job with her Manifestation Station mural on this MTA utility box. It's right at the intersection of Church St. and Duboce Ave. if you'd like to check it out.
You have to be standing at just the right point, but when you do, the street angles align with the painting on the box and the box seems to disappear, giving a little window into an alternate San Francisco.
I wonder how many pigeons have flown right into this thing. And what's in these boxes, anyway? Stacks of krugerrands and dubloons, right? Stashes of the legendary Subway Gold?