Hengchun Old City Wall (Chinese: 恆春縣城; pinyin: Héngchūn Xiànchéng) refers to the historic castle town of Hengchun, Pingtung, Taiwan. The town is known for its well-preserved city walls that surround the city, and is the only castle town in Taiwan where all of the original gates remain standing. It is protected as a national historical site.

During the Qing dynasty, the area that is modern-day Hengchun was governed as part of Fengshan County. However, being a distant and sparsely populated region, the Qing found it hard to govern the area. Things took a turn following the Rover incident and the Mudan incident, causing the Qing government to decide to maintain a stronger presence in the area. Shen Baozhen, originally dispatched to Hengchun after the Mudan incident, suggested that a fort be built in the area and named it "Hengchun", meaning "constantly spring", referring to the region's fair weather. Construction ran between 1875 and 1879 and was designed by Liu Ao, who would later design the Walls of Taipei. When completed, Hengchun became the seat of the newly-founded Hengchun County.