Located at the threshold of Saigon and adjacent to the revolutionary base, Cu Chi play and important role in the two wars of resistance against the old and new colonial powers. Cu Chi was an "underground village" with its labyrinth of interlaced tunnels having a combined length of more than 200km.The main tunnel is 60cm-70cm wide and 80cm-90cm high. The structure has either a delta-shaped or vaulted ceiling. Above the tunnel is a layer of earth about 3m-4m thick, enough to sustain the weight of 50-tonne tanks or heavy artillery as well as the destruction of bombs up to 100kg. Although it is an underground communication network, the runnel is enlarged here and there into rooms large enough to hold large meetings, a medical station or art performances.