During the Vietnam War, among the tactics used by Vietcong guerrillas to evade capture, was the digging of extensive tunnel networks, protected by hidden entrances. One of the largest of these secret underworlds survives at Cu Chi village, just north of HCMC, where visitors can explore a small section of a staggering 125 miles (200km) of cavities carved on various levels – a testament to the tenacity of the North Vietnamese forces in the face of the American onslaught. At nearby Ben Duoc, a smaller tunnel system purpose-built for tourists offers a less claustrophobic experience.