Visitors can take an entertaining and educational tour past sparkling formations, towering natural chimneys, waterfalls, and a crystal-clear stream. Special lighting effects, stereophonic sound presentations, well-trained tour guides, make up a guided tour of about 55 minutes. Forbidden Caverns has the largest wall of precious cave onyx known to exist. These caverns were inhabited several thousand years before the first European explored them. From the 1930s to 1943 they were used as a hideaway for making moonshine.