I confess that my main reason to go to Krakow was to see one of my favorite paintings, Lady With an Ermine by Leonardo da Vinci, in person and it was a dream come true. However, after doing some research I decided to spend 3 days in Krakow and visit Auschwitz/Birkenau. That also was worth seeing though definitely sobering and I'm glad I went. Wawel castle and cathedral (Church of Sts Stanislaus and Wenceslaus) is amazing and worth seeing. I did my sightseeing during the days and in the evenings I just hung out at the main square, Rynek Glowny. There was always something going on there and the market in the Cloth Hall was interesting.