Time to reveal the answer to today's Geo Quiz. We were looking for the Italian city where Leonardo Da Vinci painted his famous "Last Supper."

The answer is Milan.

"The Last Supper" was the subject of research in recent years by an Italian musician and computer tech. Giovanni Maria Pala had heard a theory that Da Vinci's mural held a hidden musical composition. He looked for clues in the painting of Jesus and the twelve apostles, sharing bread and wine, seated at a long table.

After four years' research, Pala thinks he's found what he was looking for. He's just published a book about his work. It's called "La Musica Celata" -- or "The Hidden Music."

Pala says his discovery is entirely consistent with Da Vinci's frame of mind. He notes that Da Vinci used to say that music represents the invisible. Pala says the notes are represented on the canvas by the loaves of bread and by the hands of the Apostles.

He says he focused on those two elements because -- in Catholic iconography -- the hands are used to consecrate the Eucharist -- and the loaves represent the body of Christ.

So together, he contends, they have a strong symbolic value. According to Pala, the hidden musical notation is written from right to left on the painting.