The East Gardens of the Imperial Palace

The East Gardens of the Imperial Palace were developed from the the Honmaru, Ninomaru and part of the Sanomaru of the former Edo Castle*.
Situated in the heart of the city the gardens are about 4.5 times the size of the Tokyo Dome, and allow visitors to enjoy nature all four seasons.
They include various buildings and remains of the former Edo Castle, including the castle tower, the Fujimi Tower, and Tamon.
*Edo Castle was built in 1457 and Tokugawa Ieyasu established the Tokugawa shogunate there.