The place where the Treaty of Peace and Amity between the United States and Japan was signed in 1854 was the former British Consulate General, the predecessor of the museum. Inside the museum, valuable historical materials related to the opening of Japan to the world and the opening of Yokohama's port are collected. It is said that Commodore Perry and the shogunate met under the "Tama-kusu tree" in the courtyard, which still remains to this day. In 2009, the mascot character "Tanemaru" for the 150th anniversary of the port's opening was designed as the "spirit of this Tama-kusu tree." In the adjacent Port Opening Square, the oldest brick manhole and sewer pipe in Japan are on display.
