A cave with the same temperature all year round. It's warm in winter and frosty in summer.
Be sure to take jackets and warm clothes with you - you'll freeze. Don't forget a good flashlight.
The cave consists of a long tunnel with branches, you can go through it all in about 30 minutes. You'll meet a lot of bats - try not to disturb them: don't make noise, don't touch them, don't shine your light on them :)
A place that's definitely worth visiting! A sea of impressions is guaranteed.