Tokyo is the capital and largest city of Japan, and, with a metro populace approaching 30 million, is by far the largest city in the world, though it does rank behind New York City in total area size. As the seat of Japan's government and economy, Tokyo contains important infrastructure vital to the government and nation, namely the Imperial Palace, the National Diet Building, a massive series of highways that extend far from the city itself, a subway system, and the international headquarters of the Sony, Panasonic, and Toshiba electronics corporations.