Next stop is a visit to a touristafied section of the Cu Chi Tunnel system.
During the war with the French the Vietnamese began building tunnels to move about the countryside undetected and by the time the Americans came in they had perfected the system beyond our imagination.
A repeat recommendation: read Tunnels of Cu Chi by Mangold and Penycate. You won’t be sorry. Read Neil Sheehan’s A Bright Shining Lie first though.