Tokyo , officially the Tokyo Metropolis , is the de facto capital and most populous prefecture of Japan. Located at the head of Tokyo Bay, the prefecture forms part of the Kantō region on the central Pacific coast of Japan’s main island of Honshu.Tokyo was originally a small fishing village, Edo, in what was formerly part of the old Musashi Province. Edo was first fortified by the Edo clan, in the late twelfth century. In 1457, Ota Dokan built Edo Castle .The mainland portion of Tokyo lies northwest of Tokyo Bay and measures about 90 km (56 mi) east to west and 25 km (16 mi) north to south.  In 2006, Tokyo enacted the "10 Year Project for Green Tokyo" to be realized by 2016. It set a goal of increasing roadside trees in Tokyo to 1 million (from 480,000), and adding 1,000 ha of green space 88 of which will be a new park named "Umi no Mori" (sea forest) which will be on a reclaimed island in Tokyo Bay which used to be a landfill.Tokyo has many museums. In Ueno Park, there is the Tokyo National Museum, the country's largest museum and specializing in traditional Japanese art; the National Museum of Western Art and Ueno Zoo.