Tokyo Station Marunouchi Building, designed by architect Kingo TATSUNO, was built in 1914. The building was designated as Important Cultural Property by the Government in 2003. However, the Marunouchi Building is not only a cultural property, but is indeed a full-working building that continues to be used as Station, Hotel and Art Gallery daily. Key point in design is how to keep the Authenticity and the Integrity of the building under the modern intervention for practical use.