Tucked away on the south side of Dongcun, a short walk from the former French Consulate, stands the Former Site of the French Prison in Mengzi. Locals long referred to the compound as the "Foreign Soldiers' Barracks."

Built in 1888, the facility emerged in the aftermath of the Sino-French War, right as Mengzi opened as a treaty port. The surviving architecture consists of two single-story European-style buildings constructed with a sturdy brick-and-wood framework. Yellow walls built from heavy stone blocks support striking red-tiled roofs. The first building, oriented east to west, rises seven meters high and follows a traditional three-bay spatial layout. The second, facing north to south, features a distinct rectangular fireplace chimney extending above its roofline. Originally established as an affiliated prison for the consulate, the site functioned primarily as a customs detention center during the height of foreign trade in the region.

The buildings absorbed the shifting political tides of the twentieth century. Following the establishment of the People's Republic of China, the compound found new life as a guest house for the Mengzi Military Sub-district. Preserved today as a core component of the Mengzi Customs Site, these surviving structures offer a direct window into the early modern trade history of Yunnan and the profound geopolitical shifts of the late Qing Dynasty.