Walking straight ahead you can get to an iron barrier from where the high and spacious Giant Corridor can be observed. Opposite the barrier the head of a witch can be seen. Besides opening the cave for tourists, the cave has been used for speleotherapy since 1990. Due to a constant temperature of +12 °C and nearly 100% humid ity the Saint John Hospital cures patients with asthma, allergy bronchitis and other respiratory illnesses. The self-purification of the air of the cave is proper due to the special aerosol and ion (mostly Ca-ion) combination. This means that the dust, bacteria and other polluting material brought in by visitors do not accumulate: the original cleanliness of the air regenerates itself rapidly.