Cu Chi Tunnel
Within the system of Cu Chi Tunel, Ben Duoc Tunnel was the base of Party Committee and Headquarters of Sai Gon - Cho Lon - Gia Dinh Zone & Military Zone... This is a unique architectural structure, a system of deeply underground tunnels having several floors and alleys and branches like spider web more than 250 km long for dining, living, meeting and fighting. This tunnel system embodies the strong will, intelligence, and pride of Cu Chi people, a symbol of revolutionary heroism of Vietnamese people (Source: Cu Chi Guide handed out to us during the tour)
If you are interested to go there, go to Pham Ngu Lao Street where you can find several travel agencies there. A small group tour is very recommendable because if your group will enter the tunnel, at least you don't have to wait for so many people to finish.