There are two separate tunnels underneath Guia Hill that serve its military purpose. One is 50 meters long and the longer one is about 456 meters. The facilities were constructed in 1931. The tunnels are accessible via Rampa da Guia and were converted into a museum.
松山山體內的防空地道
Not very extensive and the larger of the two that are apparently normally open wasn't open when I visited but they were cool to check out none the less. The larger tunnel could be peered into from various points such as the cannon stations and doors. I found the signage for the second tunnels extremely confusing and even after asking the staff at the cable car station he sent me in the opposite direction. The smaller tunnel that you can go into has some displays and information to check out which is good but you won't spend more than 15 minutes in there total.
在澳門保留完整的軍用隧道,隧道中也展示了歷史性的相關相片。