The Cu Chi Tunnels are 75 miles of interconnecting tunnels that were employed by the Vietnamese armed service during the Vietnamese War (or American War because they call it). They served as hiding places and as routes for communication and provides. Several troopers even lived in these tunnels for durations https://saigon94715.amoblog.com/how-much-you-need-to-expect-you-ll-pay-for-a-good-sai-gon-49918964