http://en.wikipedia.org/wiki/Leonardo_da_Vinci
http://www.scuolaleonardo.com/
_ Leonardo Da Vinci (Part 1 of 18)
http://www.youtube.com/watch?v=IQ9ar3X_u1k
_ Hidden images on money
http://www.youtube.com/watch?v=OhB8FXbmxAI
_ Leonardo Da Vinci part 2
http://www.youtube.com/watch?v=tHWLun21-_w