Photographer Michael Wesely specializes in long exposures. As in years. The above picture shows the 2001 renovation of the Museum of Modern Art in New York City and was captured over a 34-month period. You can view more examples of Wesely's work at the link.
http://itchyi.squarespace.com/thelatest/2010/7/20/the-longest-photographic-exposures-in-history.html?SSScrollPosition=232 via DudeCraft | Artist's Website | Photo: Michael Wesely