The URLs for Mona lisa:

http://www.monalisamania.com/aammain.htm
http://www.ibiblio.org/wm/paint/auth/vinci/joconde/

The URLs for Marylin Monroe:

http://www.moma.org/collection/depts/paint_sculpt/blowups/paint_sculpt_022.html
http://webexhibits.org/colorart/marilyns.html