There should be a Christmas market going on there about now. Sorry, can't give directions. It was quite a long time ago that I was there. There are museums dedicated to the Prague Spring uprising, and also the Museum of medieval torture instruments (https://www.museumtorture.com/). You can arrange a trip to Terezin (theresienstadt), if you are interested in WWII things.
Thanks for your recommendation! I love history and it seems like Prague is the perfect place:) Putting your suggestions on my list!