This is the oldest existing Western-style building in Shimonoseki, built in 1900, and Japan's oldest among post offices that are still in use and designated as a tangible cultural property. The brick walls of this building are very solid and 60 centimeters thick.  The building was designed by architect Mitsuhashi Shiro. When it was constructed, the modern design of the building attracted public attention so strongly that many people came to see it from remote places, carrying a lunch with them. In this post office, related historical materials are exhibited in a section, and a gallery with a cafe and courtyard is used as an event venue.