The first cathedral built in Poland (968), several times destroyed and rebuilt, this is a Gothic basilica with three naves, and two bell towers crowned with Baroque domes. Inside, the Golden Chapel, which was modelled on the Byzantine style in the 19C, holds the sarcophagus and statues of Mieszko I and his son, King Boleslaw Chrobry. In the crypt, there are traces of the early Romanesque building, and original tombs of the two sovereigns.