Kokyo is the Japanese Imperial palace. It was the former seat of the Tokugawa shogunate during the Edo period. After the Meiji Restoration, the Imperial court moved to Tokyo from Kyoto and the former Tokugawa stronghold became the residence of the Emperor of Japan.
It was destroyed during the Second World War, but was quickly rebuilt in the same style.
Most of the palace is generally off limits to the public, but the East Gardens are usually accessible to tourists.