Cu Chi Tunnels are located approximately 30 km northwest of Ho Chi Minh City (Saigon) in Cu Chi district. This district is known nationwide as the base where the Vietnamese mounted their operations of the Tet Offensive in 1968.
Cu Chi Tunnels consist of more than 200 km of underground tunnels. This main axis system has many branches connecting to underground hideouts, shelters, and entrances to other tunnels.
The tunnels are between 0.5 to 1 m wide, just enough space for a person to walk along by bending or dragging; however, parts of the tunnels have been modified to accommodate visitors.
The upper soil layer is between 3 to 4 m thick and can support the weight of a 50-ton tank and the damage of light cannons and bombs. The underground network provided sleeping quarters, meeting rooms, hospitals, and other social rooms. Visiting the Cu Chi Tunnels provides a better understanding of the prolonged resistance war of the Vietnamese people and also of the persistent and clever character of the Vietnamese nation. 

The two photos above demonstrate one of the reasons the tunnel system was so effective against the Australian and U.S. military during the war. Both photos were taken from exactly the same place - the tunnels are extremely well camouflaged.