Tokyo Metropolitan Government

The Tokyo Metropolitan Government Building , also referred to as Tokyo City Hall or Tochō (都庁) for short, houses the headquarters of the Tokyo Metropolitan Government, which governs not only the 23 wards, but also the cities, towns and villages that make up Tokyo as a whole.

Located in Shinjuku, it held the title of the tallest building (by roof height) in Tokyo, at 243 meters (799 feet), from 1991 to late 2006, when it surrendered its title upon the completion of Midtown Tower. The two top-floor panoramic observation decks are free of charge to the public and contain many gift shops. They are open till 11 pm on weekdays. Use of cameras is permitted, but tripods are forbidden.

The building consists of a complex of three structures, each taking up a city block. The tallest and most prominent of the three is Tokyo Metropolitan Main building No.1, a tower 48 stories tall that splits into two sections at the 33rd floor. The building also has three levels below ground. The design of the building (which was meant to resemble a computer chip), by architect Kenzo Tange (and associates), has many symbolic touches, most notably the aforementioned split which re-creates the look of a Gothic cathedral.

Finished in 1991 at the expense of 157 billion yen (about US$ 1 billion) of public money, a popular nickname for Tochō is "Tax Tower".

The other two buildings in the complex are the eight-story Tokyo Metropolitan Assembly Building (including one underground floor) and Tokyo Metropolitan Main Building No.2, which has 37 stories including three below ground.

reference
http://en.wikipedia.org/wiki/Tokyo_Metropolitan_Government_Building