In the center of Pula there is a nice flea market in the "Ciscuttijeva ulica" (Ciscuttijeva street). www.pulainfo.hr informs us:
"Every Saturday morning all year round the Antiques and Art Fair takes place in Ciscuttijeva Street in the city center (8 a.m. – 3 p.m.). It’s a great place to find antiques, interesting works of art, vintage furniture, jewelry, books, selection of coins and paper money, medals…
From 1st of July until 1st of September The Antiques and Art Fair takes place every day from 8 a.m. – 3 p.m."
Source and further information: www.pulainfo.hr/where/sajam-starina-umjetnina-u-sredistu-grada