The first incarnation of Edo Castle was built in 1457 by Ota Dokan, where the Edo family had constructed their residence in the early twelfth century. It is said that the area comprising the present Hibiya and Marunouchi districts was part of the waterfront and that fishing communities lived there. The place name Edo itself appears to signify that the area had been a fine bay. Renovation and expansion of the castle began 400 years ago, in 1603, when the Tokugawa clan established the seat of the shogunate in Edo, and it grew into Japan's largest castle in 1710. The five-story castle tower stood an impressive 51 meters high and was surrounded by as many as 111 gates. The castle has burned numerous times and was repeatedly reconstructed. In 1863, right before the dissolution of the shogunate, the main palace burned to the ground and was never rebuilt.

Today, the portion of the palace grounds now known as Kokyo Higashi Gyoen (Imperial Palace East Garden) is open to the public. This Japanese garden is an ideal place to take a stroll. Within the garden is the Sannomaru Shozokan, a museum that displays paintings, documents, and handcrafted objects handed down through the Imperial family over the generations. It is well worth stopping in to view the collection.