Outside Saigon, in an area called the Iron Triangle, the VC forces had a complex underground tunnel system.
The Cu Chi tunnel complex near the Iron Trianlge was a staggering feat of enginereering which gave the Viet Cong the advantage of virtually impermeable subterranean fortress from which to launch attacks. While U.S Army records state that 525 tunnels were destroyed during Cedar Falls (a major operation in the area 1967), this was merely the tip of the Iceberg.

The pictures shown here are from the area as it looks today. A big outdoor museum where you can go down in some tunnels and get a feeling how it was to stay down there for a long period. Also, you can see some exhibitions of bobytraps that was used by the Vietnamese against the Americans.

Click here for pictures