Kasumigaseki (Government District)
The imposition of "unequal treaties" on Japan by the West in the 1850's and 1860's provided the impetus to modernize (i.e. "Westernize") the nation's legal codes and government institutions. The proclamation of the new Meiji Constitution in 1889 marked the the end of nearly 50 years of extra-territorial concessions to Western powers, and the formal end of 250 years of feudal, clan-oriented rule by the Tokugawa family. Hanbatsu [def: clan] authority was instead replaced by the restoration of Imperial power and the formation of a parlimentary monarchy based on English and German models. Concurrent with the creation of a modern Western-influenced bureaucracy was the construction of Western-influenced buildings from which the new bureaucrats would supervise and administrate Japan's modernization.
As Japan began its modernization, the Meiji government first set land aside at Hibiya for a kanchogai [def: government village] but engineers found the reclaimed land too soft to support the weight of the planned structures. (The area, originally an inlet of Tokyo Bay, had been reclaimed from the bay using landfill collected during the massive Kanda canal project completed in the 17th century.) Land further to the west, at Kasumigaseki [def: Gate of Mist], was instead repossessed from former daimyo estates.
These grounds, along with other daimyo acreage encircling the Imperial Palace grounds, would be those upon which the Meiji government would literally build its government. Unlike the latter years of the Meiji era, when ministries and other offices of government were sited in a perimeter around the Imperial Palace, today all three branches of the government -- the legislative, judiciary, and executive -- are located within the confines of the Kasumigaseki district. Of the original late Meiji era ministries, it is only the Justice Ministry that remains on the same site today as it did in 1910.