The true to original copy of the Last Supper of Leonard Da Vinci is located in Vienna. It contains encoded messages as those in the thriller of Dan Brown “The Da Vinci Code”.
Where are there more secret codes and number mysticisms behind the facades of the city regarding the Holy Grail and the Knights Templar?
Source: Secretive Da-Vinci-Code in Vienna, R. Bouchal, G. Lukacs: