Lung Cu flagpole is a national flagpole located at Lung Cu peak, also known as Dragon mountain (Long Son) with an altitude of about 1,470 m above sea level, in Lung Cu commune, Dong Van district, Ha Giang province. , where the Northernmost Observatory in Vietnam_about 3.3Km from the North Pole of Vietnam as the crow flies. From the top of the flagpole looking down at the ground, there are 02 ponds on both sides of the mountain that never run dry all year round, called dragon's eye, is a source of water for the ethnic minorities in the two villages to use.