Located in the capital, Naha, the Okinawa Prefectural Museum & Art Museum share the same massive structure and have a common lobby.
It opened in 2007 and was designed by Ishimoto Architetcural & Engineering, a company founded in 1927 by Kikuji Ishimoto, a contributor to the New Architectural Secession Movement.
It's made out of local limestone and is modelled on the forms of the gusuku, traditional Okinawan castles. In bright sunshine it appears almost white, but in other conditions looks quite drab.
Both museums are worth a visit if you are in Naha.