Krakow is a very busy city. The medieval architecture is beautiful. There is an amazing free walking tour. If you like to go out to nightclubs and stuff this is the perfect place for you, since it is crowded even at night. There are two (and more) nice trips you can do: to the Auschwitz concentration camp (by Cracow City Tours, 90 zloty. It's worth it. The guide didn't make it too depressing, but mostly historical. Definitely recommend it.) and to the salt mine (didn't go, but very well rated).