The St. Peter's altar was built in 1695-1703. Its author was Baltazar Fontana and his workshop. An innovative type of reredos in Poland – with a pair of angels flanking a painting, was taken from the Roman art. The altars in the Church of Santa Maria del Popolo, most probably created to the designs of Giovanni Lorenzo Bernini, were the source of inspiration. Modeling angels in an expressive way, with wave-shaped draperies, the artist was inspired by statues on the Angel's Bridge in Rome, and, above all, Bernini's angels in the Church of San Andrea della Fratte.
Józef Skrabski, "Altar in St. Peter's Chapel", [in:] "The Sacred Lesser Poland Heritage", 2021, source: https://sdm.upjp2.edu.pl/en/works/altar-in-st-peters-chapel