National Diet Building
The Diet Building was completed in 1936 and is constructed purely out of Japanese building materials, with the exception of the stained glass, door locks, and pneumatic tube system.
The construction of the building for the old Imperial Diet began in 1920; however, plans for the building date back to the late 1880s. The Diet met in temporary structures for the first fifty years of its existence because there was no agreement over what form its building should take.
German architects Wilhelm Böckmann and Hermann Ende were invited to Tokyo in 1886 and 1887, respectively. They drew up two plans for a Diet building. Böckmann's initial plan was a masonry structure with a dome and flanking wings, similar to other legislatures of the era, which would form the core of a large "government ring" south of the Imperial Palace. However, at the time there was public resistance in Japan to Foreign Minister Inoue Kaoru's internationalist policies, and so the architects submitted a more "Japanese" design as well, substituting traditional Japanese architectural features for many parts of the building. Ende and Böckmann's Diet Building was never built, but their other "government ring" designs were used for the Tokyo District Court and Ministry of Justice buildings.
In 1898, Prime Minister Itō Hirobumi interviewed American Ralph Adams Cram, who proposed a more "Oriental" design for the building, featuring tiled roofs and a large enclosure of walls and gates. The Itō government fell as Cram was en route to the United States, and the project was dropped.
First building (1890) and second building (1891)
With an internal deadline approaching, the government enlisted Ende and Böckmann associate Adolph Stegmueller and Japanese architect Yoshii Shigenori to design a temporary structure. The building, a two-story, European-style wooden structure, opened in November 1890 on a site in Hibiya.
An electrical fire burned down the first building in January 1891, only two months later. Another Ende and Böckmann associate, Oscar Tietze, joined Yoshii to design its replacement. The second building was larger than the first, but followed a similar design: it housed the Diet until 1925.
In 1910, the Finance Ministry started a commission in an attempt to take control over the new Diet Building design from the Home Ministry. Prime Minister Katsura Tarō chaired the commission, which recommended that the new building emulate an Italian Renaissance architectural style. This recommendation was criticized by many who thought that choice to be too arbitrary.
The ministry sponsored a public design competition in 1918, and 118 designs were submitted for the new building. The first prize winner, Watanabe Fukuzo, produced a design similar to Ende and Böckmann's.
The Diet Building was eventually constructed between 1920 to 1936 with a floor plan based on Fukuzo's entry. The roof and tower of the building might have been inspired by another entrant, third prize winner Takeuchi Shinshichi, and are believed to have been chosen because they reflected a more modern hybrid architecture than the purely European and East Asian designs proposed by other architects. While the actual source for the "Pyramid" roof remains unclear, Japanese historian Jonathan Reynolds suggests it was "probably borrowed" from Shinshichi although an image of the entry is not provided but instead he thanks fellow historian of Africa studies at Columbia, Zoe Strother, for mentioning that Shinshichi's design resembles the Mausoleum at Halicarnassus which was a model for some prominent Western designs in the early 1900s such as John Russell Pope's 1911 award-winning House of the Temple in Washington, D.C.  and the downtown Los Angeles City Hall, completed in 1928.
House of Councillors website – National Diet Building: http://www.sangiin.go.jp/eng/guide/national/index.htm