This tunnel on the cusp of Guoliang village offers a closer perspective on the plunging cliffs, with dramatic views carved through the rock. The tunnel was built between 1972 and 1978 by a local man called Shen Mingxin (with help from other villagers). It's an incredible feat of engineering: much of the corridor was excavated by hand, using eight-pound hammers and steel bars forged by the village blacksmith.