tunnel systems
Subterranean passage complexes
Tunnel systems are networks of underground passages, whether natural formations like cave systems or constructed ones like subway networks, military bunkers, or smuggling routes.
The term often appears in discussions of warfare, where tunnel systems provide concealment and strategic advantage: The guerrillas used an elaborate tunnel system to move supplies.
Animal burrows—ant colonies, prairie dog towns—are also tunnel systems.
- catacombsUnderground cemetery passages
- smuggling routesPaths for illegal transport
- lava tubesTunnels formed by flowing magma
- boring machinesTools that cut tunnels
- excavationAct of unearthing
subterranean rivers · fortifications · warren · tunneling · underground bunkers · burrowing · digging deep · aquifers · rabbit hole · mine shafts · ancient aqueducts · archaeological sites · civil engineering · command centers · ventilation shafts · air shafts · mine · shaft
- Underground placescatacombs, bunkers, bomb shelters, metro stations, salt mines
- Vietnam WarVietnam War, Vietnam, Tet Offensive, My Lai Massacre, Viet Cong
- jungle warfareguerrilla tactics, dense foliage, jungle boots, machete, infiltration
- Viet CongViet Cong, VC, Charlie, guerrillas, guerrilla fighters
- VietnamVietnam, Saigon, Hanoi, Ho Chi Minh City, Da Nang
- resistanceresistance, defiance, resistance fighters, civil resistance, resist
tunnel systemselevated railways
Overhead urban train systems
skyways · overpasses · surface streets · sky bridges · viaducts
tunnel systemsviaducts
Elevated bridges over valleys
overpasses · aqueducts · causeways · flyovers · suspension bridges