Saiki Castle, also known as Tsuruya Castle, was a hill top style Japanese Castle in Saiki Oita Prefecture. Mori Takamasa ordered the construction of Saiki Castle and it was completed in 1606. Saiki Castle was a large castle featuring a three story donjon, five double story turrets, a single story turret and seven gates. In 1617 the donjon was destroyed by fire, but the Mori clan continued to use Saiki Castle until the Meiji Restoration. Today only one gate and some of the stone walls remain.