HaGiang is a province in northern Vietnam, bordering China. It's known for its forested limestone and granite mountains. The laid-back provincial capital, also called Hà Giang, sits on the Lô river. North of the capital, the Quản Bạ Valley has green hills and caves, and is the location of the Quản Bạ pass, also known as Heaven's Gate for its panoramic views over terraced rice fields below.