officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area in the world. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family. Tokyo is in the Kantō region on the southeastern side of the main island Honshu and includes the Izu Islands and Ogasawara Islands. Tokyo Metropolis was formed in 1943 from the merger of the former and the .
The Tokyo Metropolitan government administers the 23 special wards of Tokyo (each governed as a city), which cover the area that was the city of Tokyo, as well as 39 municipalities in the western part of the prefecture and the two outlying island chains. The population of the special wards is over 8 million people, with the total population of the prefecture exceeding 13 million. The prefecture is part of the world's most populous metropolitan area with upwards of 35 million people and the world's largest urban agglomeration economy with a GDP of US$1.479 trillion at purchasing power parity in 2008, ahead of New York City metropolitan area, which ranks second on the list. The city hosts 51 of the Fortune Global 500 companies, the highest number of any city.
Tokyo has been described as one of the three "command centers" for the world economy, along with New York City and London. The city is considered an alpha+ world city, listed by the GaWC's 2008 inventory and ranked fourth among global cities by A.T. Kearney's 2012 Global Cities Index. In 2012 Tokyo was named the most expensive city for expatriates, according to the Mercer and Economist Intelligence Unit cost-of-living surveys, and in 2009 named the third Most Liveable City and the World’s Most Livable Megalopolis by the magazine Monocle. The Michelin Guide has awarded Tokyo by far the most Michelin stars of any city in the world. Tokyo hosted the 1964 Summer Olympics and is currently a candidate city for the 2020 Summer Olympic Games.
Edo was first fortified by the Edo clan, in the late twelfth century. In 1457, Ōta Dōkan built Edo Castle. In 1590, Tokugawa Ieyasu made Edo his base and when he became shogun in 1603, the town became the center of his nationwide military government. During the subsequent Edo period, Edo grew into one of the largest cities in the world with a population topping one million by the 18th century. Tokyo became the de facto capital of Japan even while the emperor lived in Kyoto, the imperial capital. After about 263 years, the shogunate was overthrown under the banner of restoring imperial rule. In 1869, the 17-year-old Emperor Meiji moved to Edo. Tokyo was already the nation's political and cultural center, and the emperor's residence made it a de facto imperial capital as well, with the former Edo Castle becoming the Imperial Palace. The city of Tokyo was established, and continued to be the capital until it was abolished as a municipality in 1943 and merged with the "Metropolitan Prefecture" of Tokyo.
Central Tokyo, like Osaka, has been designed since about 1900 to be centered on major railway stations in a high-density fashion, so suburban railways were built relatively cheaply at street level and with their own right-of-way. This differs from many cities in the United States that are low-density and automobile-centric. Though expressways have been built in Tokyo, the basic design has not changed.
After the war, Tokyo was completely rebuilt, and was showcased to the world during the 1964 Summer Olympics. The 1970s brought new high-rise developments such as Sunshine 60, a new and controversial airport at Narita in 1978 (some distance outside city limits), and a population increase to about 11 million (in the metropolitan area).
Tokyo's subway and commuter rail network became one of the busiest in the world as more and more people moved to the area. In the 1980s, real estate prices skyrocketed during a real estate and debt bubble. The bubble burst in the early 1990s, and many companies, banks, and individuals were caught with mortgage backed debts while real estate was shrinking in value. A major recession followed, making the 1990s Japan's "Lost Decade" from which it is now slowly recovering.
Tokyo still sees new urban developments on large lots of less profitable land. Recent projects include Ebisu Garden Place, Tennozu Isle, Shiodome, Roppongi Hills, Shinagawa (now also a Shinkansen station), and the Marunouchi side of Tokyo Station. Buildings of significance are demolished for more up-to-date shopping facilities such as Omotesando Hills.
Land reclamation projects in Tokyo have also been going on for centuries. The most prominent is the Odaiba area, now a major shopping and entertainment center. Various plans have been proposed for transferring national government functions from Tokyo to secondary capitals in other regions of Japan, in order to slow down rapid development in Tokyo and revitalize economically lagging areas of the country. These plans have been controversial within Japan and have yet to be realized.
The 2011 Tōhoku earthquake and tsunami that devastated much of the northeastern coast of Honshu was felt in Tokyo. However, due to Tokyo's earthquake-resistant infrastructure, damage in Tokyo was very minor compared to areas directly hit by the tsunami, although activity in the city was largely halted. The subsequent nuclear crisis caused by the tsunami has also largely left Tokyo unaffected, despite occasional spikes in radiation levels.