The hilltop palace of the Ryukyu Kingdom, which ruled Okinawa as an independent state for 450 years before Japan annexed it in 1879. Fire destroyed the main hall in 2019 and the rebuild finishes this year. The Seiden reopens on 23 November 2026 and admission rises from 400 to 1,000 yen the same day, so the timing of your visit decides both what you see and what you pay. The stone walls, gates and Ryutan pond are open either way.