The Golden Ratio is discussed at this site:

http://www.geom.uiuc.edu/~demo5337/s97b/art.htm

The Golden Section in Nature is discussed at this site:

http://www.gi.alaska.edu/ScienceForum/ASF7/716.html

There are many sites that discuss the relationship between math and art (that is between perspective and projective geometry). You need to look at sites that are not heavily weighted by mathematical notation. One such site is:

http://mathforum.org/sum95/math_and/perspective/perspect.html

This site explores Saccheri’s quadrilateral:

http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Non-Euclidean_geometry.html