Around 25km north of Dong Van and right on the Chinese border, Lung Cu is a massive flag tower erected in 2010 to mark the northernmost point of Vietnam. The summit is reached by almost 300 steps from a mid-level carpark, and the views across rural villages are stunning. You'll need to show your passport and Ha Giang permit twice – at the local tourist police and army checkpoint near the base of the tower – before ascending to the top.
