This image of the 'West Ponente' direction marker in St. Peter's Square (just in front of St. Peter's Basilica) was considered for use in the 2009 History Channel documentary, Angels & Demons Decoded. Read more about another one of my photos' use in that documentary here: Photo Used in History Channel Documentary.
There are three other direction markers, and, according to the documentary's producers, all the markers stood for different elements of the world. This marker stands for air, or wind. (Notice the flowing hair, and the lines of air exiting the angel's mouth).
This photo, on Flickr, was actually used in the documentary.