The two-story wooden main building was designated a National Important Cultural Property in 1974, and the annex building (caretaker's office) was designated an Important Cultural Property in 1980. The building was reopened on April 26, 2021.

While the exterior of the building is impressive as a whole, the details of the building, such as the roof windows, the decorative fence, the pediment, the columns, and the decorations at the tops of the columns, are all very high-caliber. The noble atmosphere of the interior is especially striking in the guest room on the second floor, which has been used by the royal family, with its foreign wallpaper, chandeliers, fireplace, and other furnishings.

In addition to the extensive exhibits that explain the history of the public hall and the building's features, the "Costume Hall" is also popular, where visitors can experience the exotic atmosphere by wearing long, glossy dresses and high-collar-style costumes. Visitors can also experience the exotic atmosphere of the "Costume Hall," where they can dress up in long, glamorous dresses or high-collar style costumes. The museum also has a store with a wide selection of Hakodate's unique products, and is a great place to look for souvenirs.