Nam Tun archaeological site in Muong Xo commune, Phong Tho district, Lai Chau province is classified as a National Monument by the Ministry of Culture, Sports and Tourism.

Nam Tun archaeological site in Phong Tho town, Lai Chau province. Excavated in 1973, the cultural layer 1.8 m thick has two layers. The upper layer has grinding stone axes, pottery and 3 tombs (remaining remains) typical for the Neolithic period. The lower layer has found nearly 200 crudely hewn pebble tools, large size, over 700 pieces and 2 tombs typical for the Late Paleolithic period, representing the oldest cave archeological relic in the Northwest, belonging to Son Vi culture.

Nam Tun cave site is the place of residence, burial and tool-making of two classes of people, with two layers of culture, the pre- and post- Neolithic period. In Nam Tun cave, there are 5 ancient tombs and many ancient relics, especially the bone awl, first found in Vietnam.

Archaeological relic of Nam Tun cave is ranked as a National Monument of very important significance; not only to restore and embellish, promote the full value of the site but also the pride of the nation and affirm national sovereignty.