지쿠젠 국
was a Japanese castle in Chikuzen Province, in the north of Kyūshū. It was at the peak of Mount Tachibana, extending in part into the Higashi-ku in Fukuoka. The castle is also known as Rikka-jō, Tachibanayama-jō, or Rikkasan-jō (立花山城, "Tachibana mountain castle").