The Cu Chi Tunnels are 75 miles of interconnecting tunnels that were used by the Vietnamese military during the Vietnamese War (or American War as they connect with it). They served as hiding spots and as routes for conversation and materials. A lot of troopers even lived in these tunnels https://collinrvxyx.thekatyblog.com/29400509/5-tips-about-sai-gon-list-you-can-use-today