These frescoes were created by masters from the Lombard School around 1430: the life of St. Stephen covers the North wall, the adoration of the Magi, apostles and evangelists lights up the presbytery, and the triumphal arch features the martyrdom of St. Ursula and the crucifixion with the saints. In contrast, the colourful passion cycle and the depiction of the Last Judgement on the South and West walls were created by a Swabian workshop around the year 1487.
An unusual feature of the chapel consists of the graffiti left by pious visitors in the 15th and 16th centuries.