The gusuku castle sites are certainly a must for anybody interested in visiting castles, castle ruins - in particular, Japanese castles. Shuri Castle is quite impressive, although it's just a copy of the original that was lost to WWII, it's one of the most beautifullest places on the island of Okinawa and certainly is a gem. The other castles such as Nakagusuku and Nakajin and Zakimi are ruins and are worth also the visit. Nakagusuku castle ruins are also known as the "haunted castle" and the ruins are beautiful. You can walk around the castle grounds and view the surroundings and scenery. Next to the castle ruins are the modern ruins of the haunted hotel that was burnt over 20 years ago which remains intact. A walk up to the viewing tower of the hotel will give you a spectacular view of the island's western side and castle grounds. To better experience the haunted feeling of the Nakagusuku and the haunted hotel is at night (bring a flashlight). Nakajin Castle and Zakimi Castle have beautiful views as well when you stand on their walls.