Whole mine is sculpted from the salt. So simple but beautiful. Hard work of thousands of people through the centuries surprise and delights that human kind is able to create such a beauty only from salt.
Definitely if you're planning to visit Krakow, please consider to check Wieliczka as well. You won't be disappointed !
For me the most incredible part of Wieliczka is The Chapel of St. Kinga - you can even get marry there ! ( booking minimum 3 years before ;)