The gigantic Buddha of Nara, in Japan, is one of the greatest examples in the world where a scientific approach based on modern experimental paradigms succeeds to shed light on ancient realizations of mankind. Copper-gilded statues worldwide belong to cultural heritage, and gilding technologies involve some common expertise procedures which allow us to establish a close connection with present sophisticated nanotechnology techniques. To unveil the old mystery of Great Buddha of Nara gives us an excellent example how corrosion protection technology is performed using copper/gold amalgam gilding. The experiments of oxidation of Cu3Au modeling the surface of Buddha, using modern surface science techniques, demonstrates the protective nature against the bulk oxidation, induced by Au atoms. Thus, art and knowledge have been always interconnected and scientific analysis by experiment can successfully test archeological hypothesis.