Recommendations for Zagreb???

Next week I will be in Zagreb, Croatia delivering a Workflow Training session to a great Captaris partner.The session takes 2.5–3 days but then the evenings as well as Sunday evening and Thursday morning are free. I know I will get recommendations from the people in the class, but want to know if anyone reading this has any favorite spots in Zagreb. Personally I will consider the trip a success if the class participants learn something and if I don’t step on a landmine. I think most people do learn a few tricks in class, and the US State Department says that Zagreb and other major city areas in Croatia are safe (landmines can apparently still be found in some less populous areas), so there is a very good chance of achieving that success. If I can see some amazing sights in a wonderful city like Zagreb, all the better.