On November 16, 2005 a parking space in San Fransisco was subliminally hacked.
At noon, the parking-space transformed into a small public park with grass, a tree and a bench where people could rest and relax. After two hours, the park turned back into a parking space.
The urban intervention was performed by Rebar group without any interference from the local authorities.
Original Post: http://www.guerrilla-innovation.com/archives/2005/12/000466.php