St Mary’s Chapel was built on the axis of the cathedral. The chapel is covered with extremely impressive nine-field vaulting, and echoes the layout used in the eastern chancel and the ambulatory of the cathedral. Its interior was adorned with the rich painted Byzantine-Ruthenian decoration, dating from the times of Władysław Jagiełło. The king often employed workshops from Ruthenia for decoration. Their works are in the most important churches in Poland (e.g., the metropolitan cathedral in Gniezno, the collegiate churches in Sandomierz and Wiślica and the castle chapel in Lublin). This consistent reaching out to the models of Orthodox art was attempted to be explained, inter alia, as efforts to unite the Western and the Eastern Church. However, already Jan Długosz in his Chronicles stated that Jagiełło “preferred Orthodox art over Latin art”, which can be considered as the manifestation of a specific taste.
We are all well aware that to enter this Cathedral can not be without emotion. More I say, you can not enter it without the internal tremor, without fear because it contains in it - as in almost no Cathedral of the world - the enormous size, which speaks to us in all our history, our entire past.cardinal Karol Wojtyla