Consisting of Western-style house, Japanese-style house, and gardens, 6 buildings and grounds of Kakkien were designated Important Cultural Property in 2002 by virtue that 'it is a rare example that completely conveys the style of a late-Meiji era mansion'.
洋館と和館、庭園からなり、「明治後期の大邸宅の姿を完全に伝える稀有な例」として2002年（平成14年）に建物6棟と土地が重要文化財に指定された。