We spent a day visiting the Cu Chi tunnels in Ben Dinh. These tunnels were built over a 25 year period starting in the late 1940's and ended up covering 420 sq km. The Vietnamese used these tunnels to hide in the American war. The tunnels were difficult to detect. Some had wooden trap doors camouflaged with earth and branches.The tunnels were 1.2m high and 80 cm across and were unlit. Not very inviting - girls went into them. I went down one but had to come out pretty quickly- felt close to having my first ever panic attack!!