- Tokyo (東京) officially Tokyo Metropolis (東京都), one of the 47 prefectures of Japan, has served as the Japanese capital since 1869.
- As of 2018, the Greater Tokyo Area ranked as the most populous metropolitan area in the world.
- The urban area houses the seat of the Emperor of Japan, of the Japanese government and of the National Diet. Tokyo forms part of the Kantō region on the southeastern side of Japan's main island, Honshu, and includes the Izu Islands and Ogasawara Islands.
- Tokyo was formerly named Edo when Shōgun Tokugawa Ieyasu made the city his headquarters in 1603.
- It became the capital after Emperor Meiji moved his seat to the city from Kyoto in 1868; at that time Edo was renamed Tokyo.
- As of October 1, 2015, the population of Tokyo is estimated to be over 13.4 million, or about 11% of Japan's total population.
- Tokyo ranks first in the Global Economic Power Index and third in the Global Cities Index.
- Tokyo has the largest metropolitan economy in the world. According to a study conducted by PricewaterhouseCoopers, the Greater Tokyo Area (Tokyo-Yokohama) of 38 million people had a total GDP of $2 trillion in 2012 (at purchasing power parity), which topped that list.
- Architecture in Tokyo has largely been shaped by Tokyo's history. Twice in recent history has the metropolis been left in ruins: first in the 1923 Great Kantō earthquake and later after extensive firebombing in World War II.
- Tokyo has enacted a measure to cut greenhouse gases. Governor Shintaro Ishihara created Japan's first emissions cap system, aiming to reduce greenhouse gas emission by a total of 25% by 2020 from the 2000 level.