St. Peter's and Paul's Cathedral - the first Polish cathedral and the only one between years 968 and 1000. Burial place of 8 Polish dukes and kings from the Piast dynasty - original graves from 10th and 11th centuries of Mesko I and his son Boleslaus the Brave preserced in the cellar; as well as the baptism bowl - a probable baptism place of Duke Mesko I. In the cathedral pay attention to the chain of chapels around the main aisle, not touched by bombings in 1945 - the most precious ones are: the Golden Chapel (which a present memorial place of Mesko I and Boleslaus the Brave - in the sarcophagus on the right-hand side) and the Holy Cross Chapel.