There are two large and beautiful caves in the suburbs of Lang Son. Both are illuminated, which makes for easy exploration, and have Buddhist altars inside. Tam Thanh Cave is vast and seductive. There’s an internal pool and a viewing point or natural ‘window’ offering a sweeping view of the surrounding rice fields. Just a few hundred metres up a stone staircase are the ruins of the Mac Dynasty Citadel . It’s a lovely, deserted spot, with stunning views across the countryside. The Nhi Thanh Cave entrance has a series of carved poems written by the cave’s discoverer, a soldier called Ngo Thi San, in the 18th century. There’s also a carved stone plaque commemorating an early French resident of Lang Son, complete with his silhouette in European clothing.
