Otani’s design won the major competition, for which there were almost 200 entries. Otani chose a trapezoidal shape as the basis for the huge conference center. The shape is repeated on different scales and thrusts throughout the complex. The different functions such as the conference, press, administrative and visitor areas are organized across different levels. The exposed concrete serves in part to clad the load-bearing steel structure. At the time, the execution of the concrete set new standards, even in Japan (A. Forty).

Expansion building 1973, several restoration phases 1973, 1985, 1998. Current modernization ongoing since 2011.