Subway museum is located in Edogawa ward, Tokyo, close to Kasai station on Tokyo Metro Tozai line and it is the only museum in Japan specialized in subway (metro) train and its system.
Then, you can find the oldest Japanese subway train which was running on Ginza line at the museum. Ginza line is the oldest subway line in Asia, which opened in 1927, before WWII. Actually there are only two subway lines in Asia which before WWII.
Also you can learn also the subway system and other details related to subway, including histories not only Japan but also other countries which have subway.
Subway museum is open daily except Mondays and some information are also written in English too.