long narrow tunnel in medieval castle

access adventurous ages ancient architectural architecture backdrop brickwork building castle construction covertly creepy dark defense destination eerie europe european excursion exploration explore follow fort fortification fortified fortress germany hide hiding historical history inside long medieval middle military mysterious mystery mystical narrow old passage passageway path place preserved ruin secret shafts site spooky stonework structure sunlight system thrill tour track trail travel tunnel tunneling walkabout walls way light darkness hope