The altar in St. Sebastian's chapel was built in 1695-1703. Its structure and sculptural decoration were made by Baltazar Fontana and his workshop. The innovative type of reredos, in the form of an oval painting flanking by angels, was inspired by Roman works from the circle of Giovanni Lorenzo Bernini (altars in the Church of Santa Maria del Popolo).
Józef Skrabski, "Altar in St. Sebastian's Chapel", [in:] "The Sacred Lesser Poland Heritage", 2024, source: https://sdm.upjp2.edu.pl/en/works/altar-in-st-sebastians-chapel