Muong So Fort was built by the French in 1917 on the top of Pu Kho Nhu (the mountain of dragons back up) to ensure security for the central garrison and guard the border area. Depending on the time, the fort had different names: the fort was called the "high point" during the French occupation; During the resistance war against the French, the fort was called Cao Cao; Later, the fortress named after the commune was Muong So.