sentences:  The city's extensive heritage entails almost all cultures of Central Europe including years of Polish, Bohemian, Prussian and German rule.Opole formally became part of Poland again in 1945 under the Potsdam Agreement.Many German Upper Silesians and Poles of German ancestry still reside in the Opole region; in the city itself, however, ethnic Germans today make up less than 3% of the population following the 1945–6 expulsions.