The Stairway at St. Paul's (2001)

Dutch visual artist Jeroen Offerman spent three months learning to sing Stairway to Heaven backwards. He then stood in front of St. Paul's Cathedral and recorded it with air guitar, head banging and all, while people strolled past him with stunned looks on their faces. He reversed his recording and added Stairway to Heaven's music track, resulting in a most amazing rendition.