It's home to (virtually) every national government ministry, agency and department. These include the Ministry of Finance, National Police Agency, Ministry of Foreign Affairs, Patent Office and Public Security Intelligence Agency (along with dozens of other Ministry headquarters).
(Ministry of Justice)
Security PresenceThere's a large police and security presence in Kasumigaseki. On March 20, 1995 a terrorist attack (Sarin gas attack) targeted trains passing through Kasumigaseki (and Nagatacho) station. The coordinated attack claimed the lives of 13 people and injured 1100.
Kasumigaseki BuildingThe Kasumigaseki Building was Japan's tallest building when it opened in 1968. It's only 30 stories high. Until 1968, Tokyo had strict building height restrictions due to the risk of earthquakes. Today, engineering advancements allow much higher buildings to be constructed that are earthquake resistant. For example, Tokyo Sky Tree is four times the height of the Kasumigaseki Building (634 meters vs 156 meters).
Area MapKasumigaseki borders the Imperial Palace, Nagatacho and Hibiya park. It's also close to Ginza (Tokyo's upscale shopping district).
Kasumigaseki is several city blocks of national government buildings to the west of Hibiya Park. There's not much shopping, dining or entertainment in the area. The neighborhood is of interest to architecture buffs and photographers. Many of these buildings have notable western style architecture.
Nagatacho is a similar district of government buildings next to Kasumigaseki. Nagatacho is home to the National Diet (Parliament) and Prime Minsters Residence.