German forces excavated this tunnel complex under Trieste after annexing the city into their Adriatic Coast Operational Zone in 1943, employing three separate construction firms through the Organisation Todt to dig air-raid shelters into the karst bedrock.
An Italian sector held parallel tunnels fitted with wooden benches, first-aid rooms and toilets for civilian use, while a separate German sector, roughly a thousand square meters and reserved for SS troops, included a secret passage that let SS-Gruppenführer Odilo Globočnik move between his residence and Trieste's courthouse unseen. German command evacuated in late April 1945, Yugoslav Partisan forces entered the city on May 1, and the occupying German garrison ultimately surrendered to New Zealand troops, closing a twenty-month occupation whose underground infrastructure survives largely intact beneath the modern city.
