The church's Gothic character disappeared at the turn of the 20C with the addition of Art nouveau stained-glass and murals by Stanisław Wyspiański, for which the building is now renowned. The frescoes depict floral, geometric and heraldic motifs plus some figurative scenes and cover the chancel and transept walls. Note the chapel of the Passion of Christ, from where the brotherhood of the same name (also called Of Good Death) sets off each Good Friday in an impressive procession.