If you go near Carcassonne, please visit this cave, the Cabrespine. Near this grotto, you can see Limousis grotto too, but Cabrespine is amazing, a twenty minute drive from the medieval city of Carcassonne. The price of entry is 9 euros, stings a little, but it is worth it. Reached by winding mountain roads, once there, entry is via steel doors and stone walls. Inside, you run out of words. There are some machines that explain the history of the cave. The tour does not take long. I hope you like my experience. You could find discounts to visit the cave throughout the medieval city.