Zadar, a ferry ride south from Pula, is a fantastic place to visit. I stayed in a hostel overlooking one of the most impressive parts of the town, the Roman forum, but within a short walk are lots of great things to see.
There is a very interesting museum of Roman glass, with thousands of pieces both small and large, sorted into groups based on usage – domestic, burial, rare glass etc. Unfortunately they are one of those museums which ban photographs, so I can’t show you any examples of these.
There is also a lovely place to spend a summer evening at the end of town – you can watch the sun set into the sea to the sound of a Sea Organ, which makes music as the sea water rushes into it.