Mammoth cave, a UNESCO World Heritage Site, is the world’s longest cave system with more than 400 miles of surveyed passageways (estimates that around 600 miles are unexplored). This is a subterranean world of immense rooms, long canyons, and tight passageways and that is the reason it is called a “grand, gloomy, and peculiar place”The history of the cave goes back to over 10,000 years. Cave exploration dates back to 4000 years and the artifacts they left - like cane reed torches which they used to light the pathway are preserved in drier passageways.Throughout the spelunking, rangers explain the geology and history of the cave. The cave through which we walk was once a river. It flowed through this passageways until an easier path led it into the depths below. Another peculiarity of the place is that it maintains a 12-degree Celsius temperature round the year. The air conditioning is maintained deep below the ground level.In order to explore Mammoth Cave, you must join a tour. More than a dozen number of tours are available at different time slots. In a tour, you travel with a tightly packed group so that the rangers can keep an eye on you and protect the fragile ecosystems in the cave which holds one of the world’s most diverse cave ecosystem with about 130 forms of life. Moreover, the cave system is so vast as without a ranger, we’d be lost there forever.I joined the Grand avenue tour and the Violet city lantern tour which covered almost 7 miles of the cave.