For those interested in Vietnam War, crawling Cu Chi Tunnels (70 km/40 miles northwest of Ho Chi Minh City) is a must, if not an eye-opening experience. The original networks stretched 250 km from Saigon to the Cambodian border and served as the base for Vietnamese guerrillas to attack American troops. Major parts were destroyed by B52 bombarding in Tet offensive (1968). The section in Cu Chi District survived and has been recently enlarged for visitors to climb down. In this underground world, there is a little museum with some artifacts on display, a number of meeting chambers, shelters and even kitchens.
There are four monuments those interested in Vietnam War should not miss: the Reunification Palace and the War Remnants Museum in Ho Chi Minh City, Vinh Moc Tunnel used by local villagers and guerrillas in Quang Tri and/ or this amazing network of tunnels at Cu Chi (north of Ho Chi Minh City). Compared to Cu Chi, Vinh Moc retains its original structure and shape, yet Cu Chi is much more convenient to reach. You may visit the tunnels independently by bus or motorcycle, but joining a tour from Saigon is much easier and cheaper. Also, a good guide will show you which part of the tunnels you can crawl through and safeguard your safety.