Tokyo, largest city and capital of Japan, and one of the most heavily populated cities in the world. It is located at the head of Tokyo Bay, on the eastern coast of Honshu, the largest of the four main islands of the Japanese archipelago. The city of Tokyo proper is made up of 23 special wards (ku), with a population (1994 estimate) of 7,874,000 and an area of 570 sq km (220 sq mi). The Tokyo metropolitan prefecture (Tokyo-to), of which it is part, extends to the west of the central city and has a population of 11,631,901. The great urban sprawl, of which Tokyo is the heart, is known as the Greater Keihin Metropolitan Area, and it includes two major cities, Yokohama and Kawasaki, to the south. Tokyo has been the national capital of Japan since 1868, after the rule of the feudal Tokugawa dynasty was overthrown in the Meiji Restoration; at that time the city's name was changed from Edo. Today Tokyo is the country's financial, industrial, commercial, and cultural centre.