In December 2005, the city of Philadelphia cooperated with a group of artists to transform its late-nineteenth-century Second Empire city hall into a colorful, glowing wonderland. The effect was produced with slides and powerful projectors. Each architectural detail was set off with bright, playful colors.
http://www.bbc.co.uk/bradford/content/articles/2006/10/04/light_night_feature.shtml
Pic can be found at:
http://www.bbc.co.uk/bradford/content/images/2006/10/09/people_465x370.jpg