This incredible 150 million year old rock hollow can be found near the place called Sami and it is a true geological jewel. Despite its age and the fact that it was known to the people for centuries, it was only opened for the public in the 1960s. Inside you can see red and yellow dripstones (both stalactites and stalagmites). Todayy it serves not only as a tourist attraction but also a concert hall since it has extraordinary acoustic conditions.