Sơn Tây Fortress is a historical military structure located in Sơn Tây, a town in Hà Nội Province, Vietnam. Built in the late 19th century during the French colonial period, the fortress was designed to protect the region from potential invasions. Its architecture features a blend of European and traditional Vietnamese styles, showcasing thick walls and strategic defensive positions. The fortress covers an area of approximately 2.5 hectares and includes various buildings, such as barracks and a command center. Today, Sơn Tây Fortress serves as a popular tourist attraction, offering visitors a glimpse into Vietnam's military history and colonial past.