The high altar of the Assumption of the Virgin Mary was built in 1742-1747 and consecrated in 1749. It is in the type of a non-architectural reredos with ciborium, with suspended drapery curtains in the form most likely inspired by a heraldic mantle. It was to be distinctive for the Marian image, emphasising the royal character of the Virgin Mary. The most likely creator of the fully-sculptural high altar in Grab is Antoni Gegenbauer, who made his sculptural decoration and two statues from the reliquaries of that reredos.
Paulina Kluz, "High altar", [in:] "The Sacred Lesser Poland Heritage", 2021, source: https://sdm.upjp2.edu.pl/en/works/high-altar-43