I went for a tour of Mammoth Cave in Kentucky on August 5th. The tour I took is called the Domes and Dripstones which is about 2 hours long. It enters through an artificial entrance that was made in the 1920s. The takes you on the second level of a 7 level cave system. There are actually over 400 miles of known caves in the system and it continues to grow from the 7 rivers that run underground through the cave system. We went through some tight passage ways and into some large rooms. There are lots of interesting features in different parts of the cave.