In the Royal Chapel on the north side of the cathedral is a marble sarcophagus forming the tomb of two Polish rulers, Władysław I Herman and his son Bolesław III Wrymouth.

[2] This was the first large Renaissance style cathedral in Poland, although it reused granite ashlar portions of the Romanesque basilica.

[2] The layout of the new cathedral was based on the Renaissance basilicas of Rome (Sant'Agostino, Santa Maria del Popolo).

However the external architecture remains in the style of North Italian brick churches, more similar to local late Gothic ones in Masovia, and may be the result of rebuilding work about 1560 by Giovanni Battista of Venice, who added the spacious choir and two western towers.

[2] Between the world wars, the interior was decorated with additional frescoes by Władysław Drapiewski and Czesław Idźkiewicz, local student of Józef Mehoffer graduating from the Academy in Kraków.