Cu Chi Tunnels - Nhuan Duc, Ho Chi Minh, Vietnam

The Cu Chi district sits on a huge network of hidden tunnels. Thousands of Viet Cong soldiers spent most of their time down here, as besides tunnels there were also communication centres, hospitals and living quarters. The tunnels are not for those with claustrophobia as the entrances are often too small for the average shoulder width. Many of the tunnels were bombed by US air strikes, but those that remain can be explored with a guide.