The Old Koga Residence was built in 1884 to be the home of the founder and president of Koga Bank. After the president, his successor （Zenpei II） continued to reside there until the bank dissolved, when it changed hands, and was then used as a restaurant starting in 1954.

Unlike most other houses of the town with kirizumauzukuri^※1 style roofing, the Old Koga House is adorned with a irimoyazukuri^※2 style roof, looking similar to a bukeyashiki^※3. The large hall totalling over 50 tatami mats in size is particularly impressive. Also of particular note are the Ranma^※4, Fusuma^※5, and wooden doors.

The existing building consists mainly of well-preserved tatami rooms, and is an excellent example of an upper-class mansion of the Meiji Era.

In 1991 the building became the property of Saga City, and the parts that were changed during its time as a restaurant were restored to its original state. Four years later in 1995 it was designated as an Important Cultural Property of Saga City.