A New York artist believes he's "cracked the code" of Leonardo da Vinci's "Mona Lisa" painting. Ron Piccirillo stated on his blog that the painting is an optical illusion with one painting hidden within another. He refers to a "secret that has been hiding for five hundred years" as he claims to have found a lion's head, an ape head and a buffalo head in the painting while turning it around. "I had first Googled this, but could not find anything on it," he stated. "How could something like this have gone unnoticed for five hundred years?" The key to...