Cave National Park, Central Kentucky, USA. The longest known cave system in the world. There are over 400 miles of caves that have been explored. 63 Alabama State Parks,The first thing you notice about Cathedral Caverns is the massive entrance. The huge opening measures 126 feet wide and 25 feet high. And it gets even better. Inside the cavern, you will find Big Rock Canyon, Mystery River and some of the most beautiful formations Mother Nature has ever created. Among them, you will see Stalagmite Mountain, The Frozen Waterfall and Goliath, a huge stalagmite column that reaches the ceiling of the cave some 45 feet above!