Lang Son, a mountainous province nearby the Chinese border, is only 145km north of Hanoi. It was a place of glorious victories of the Vietnamese in their struggle of independence.

Tam Thanh Grottoes, situated near the city of Lang Son in Lang Son province, include three grottoes: Nhat Thanh, Nhi Thanh, and Tam Thanh. The most famous is Tam Thanh Grotto, lying west of Ky Lua Street. Its door is approximately 8 m high, opening to a corridor with 30 stone steps carved into the mountain. There are dense groves hiding the grotto from the sun.



 Poet Ngo Thi Si (17261780) carved one of his texts on the grotto wall while he was a Mandarin guard in Lang Son. The poem praises the magnificent natural beauty of the area, more specifically the sound of the water stream falling on hundreds of rocks, almost like a graceful murmur.
Vong Phu Mountain, meaning "waiting for a husband," is located nearby. Here, one can explore a grotto with marvelous stalactites and a statue of Buddha.
To Thi Mountain has the shape of a woman carrying the baby in her arms and waiting her husband coming back from the frontier.