The Zhangbi Underground Castle at Jiexiu, about 130 km south of Taiyuan, is one of the most unusual heritage sites in Shanxi — an ancient village built on top of a labyrinthine network of underground tunnels that extends beneath most of the settlement. The tunnels, used as escape routes and defensive shelters during periods of military threat, were first cut in the Sui dynasty and expanded over subsequent centuries. The village above is a well-preserved example of northern Chinese traditional architecture; the tunnels below are dark, low, and genuinely disorienting to walk through.
The combination of the intact above-ground village and the extensive below-ground system makes Zhangbi a more layered experience than a simple underground site would be. Guided tours through the tunnel system take about an hour; the village walk takes another hour. It is feasible as a long day trip from Taiyuan combined with a stop in Jiexiu town.