The Heidelberg Project
NOTE: This article is relatively old, and really needs a reworking both factually and in scope
The Cass Corridor is Detroit neighborhood that contains a lot of abandoned houses. Many of them are obvious, if blighted, evidence of the wealth and splendor that graced the city in the early 20th century. Tyree Guyton, an artist who lived in the area, felt the need to respond to the decay, and in the 1980s began transforming Heidelberg Street, creating what became known as The Heidelberg Project. Polka dots covered the streets and houses, and swallowed automobiles and a city bus whole. Dismembered dolls adorned houses like pink plastic gargoyles, and enormous piles of discarded furniture stretched to the skies. If this sounds odd, you're right, the sheer scale of this realm of misrule was pretty stunning. The Detroit Free Press has a photo gallery of a festival at the project, and the folks at DetroitYes.com have some more general photos; there are many more available on the web.
Of course, the Control Freaks can't live with this kind of rampant creativity. The city periodically gets tired of having an internationally-acclaimed work of art and major tourist attraction in the city, and in 1991 and 1999 it demolished several houses, the latter apparently on questionable legal grounds. It's still around, thankfully; needless to say, the neighborhood as a whole still hasn't really been addressed by the city, which owns most of the property.
Stories and Speculation
It could probably go without saying that the Heidelberg Project cries out to be recast as either an emergent portal to the fairy lands of Arcadia, or the physical manifestation of the influence of Nyarlathotep or another entity of the Cthulhu Mythos with ties to chaos and the creative impulse run amok. In either case, one could question whether merely demolishing the physical manifestation of the project would be enough to undo the warped reality underlying it.