Today we visited the Wieliczka salt mines (a UNESCO world heritage site) and not only saw how the mine operated in the past but practically a whole city 100 - 175 m below. There were amazing chapels, a cafe, a ballroom, children's play areas, toilets, etc. Lots of salt sculptures as well.
Next we went up to Wawel hill to look at the castle, cathedral and royal palace before walking back down the hill and through the Old Town to the market square (the largest in Europe and another world heritage sight). Notable sights are the Cloth Hall and St Mary's Basilica as well as the smallest church in Krakow (there are lots of churches here as Poland is 95% catholic and they also have many statues of Pope John-Paul II, born in Krakow).
We finished our day by going to a polka party - lots of traditional food (so much food!) drinks, costumes and dancing! A great night.