Go for it Marian, I second what Perplexed said about Krakow. It's a great place to visit. Ensure that you pick a centrally located hotel so that you can go out to eat in the evenings without worrying about getting back to the hotel. I visited Krakow some years ago on my own and am happy to recommend Hotel Amber which is 5/10 minutes walk from the main square. Have a look on Tripadvisor, there is so much to see and do, you will be spoilt for choice. Decide how long you think you will be happy to be on your own, say 4/5 nights might be enough. Have a great time!