Lung Cu Flag Tower stands at Vietnam's northernmost point, on a hill above the village of Lung Cu near the Chinese border. A 33-metre flagpole flies a large red flag at the summit, visible for miles across the plateau, and the climb to the tower — up several hundred steps cut into the hillside — gives a 360-degree view of the border landscape: Chinese territory on one side, Vietnamese karst plateau on the other, with remarkably little to mark the distinction except the flag itself.
The village below has a small H'mong and Lo Lo community, and it's worth walking through rather than driving straight back. The tower is usually combined with a stop at the Lung Cu border area viewpoints on the road from Dong Van, where the plateau edge gives views into China proper. The round trip from Dong Van is about two hours by motorbike, mostly on good road.