Expanded into an assembly complex during the Vietnam War, the system served Communist guerrilla fighters' needs for cover from aircraft bombardment, medical assistance, communications and supply transfers, surprise attacks, and ground-based camouflage. About 120 kilometers of the 250 kilometers that made up the Cu Chi tunnel system—which formerly extended to the Cambodian border—have been well preserved and are now accessible to the general public. The Cu Chi Tunnels Saigon complex, constructed on laterite and clay soil, astounds visitors with its remarkable durability and design. To confound and impale enemies, several intricate booby traps and phony bunkers have been put up on the bottom floor. Vietnamese individuals can barely fit through the narrow tunnel apertures; vegetation has grown above the wooden manhole covers.