The altar in St. John the Baptis's chapel 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 became the source of inspiration. The statue of an angel with raised hands, located on the left side, finds similarities in the statue of Daniel and the Lion, by Giovanni Lorenzo Bernini, located in the same Roman church, in the Chigi Chapel.
Józef Skrabski, "Altar in St. John the Baptist's Chapel", [in:] "The Sacred Lesser Poland Heritage", 2021, source: https://sdm.upjp2.edu.pl/en/works/altar-in-st-john-the-baptists-chapel