Located in Transylvania, Romania, Salina Turda is one of the oldest salt mines in the world, with excavation dating back to the Middle Ages. After commercial mining ceased in 1932, the massive caverns served as a bomb shelter during World War II and later a cheese storage facility. In 2008, a massive modernization project transformed the cavernous mine into a breathtaking underground amusement park, complete with a Ferris wheel, bowling alley, amphitheater, and boating lake located 120 meters below the surface.
Transforming a centuries-old subterranean salt void into a public attraction required specialized structural engineering and conservation techniques. The chief challenge was managing humidity and salt corrosion. High humidity combined with micro-fine salt particles causes rapid oxidation of traditional metals.
Engineers utilized specialized stainless steel, untreated wood, and high-density polymers for all interior structures, including the boardwalks and underground dock. Furthermore, to preserve the structural integrity of the massive bell-shaped chambers—such as the Terezia mine, which drops 112 meters down—engineers installed non-invasive structural monitoring systems using laser scanning and ultrasonic sensors to track wall movement without drilling extensively into the micro-crystalline salt rock. Controlled passive ventilation systems maintain a constant temperature between 11 and 12 degrees Celsius, controlling moisture without introducing high-velocity air drafts that could cause salt wall flaking.
The result is a unique fusion of medieval heritage, natural halotherapy, and sci-fi infrastructure that protects the ancient geological marvel while hosting thousands of visitors daily.