[1] The Duomo Museum was inaugurated in 1987 and set up in what was the medieval hall of the Collegiate Church of Santa Maria Maggiore, the city's cathedral, which was later transformed into a crypt following the construction of the staircase and the elevation of the nave.

[2] It was established at the behest of Parish Priest Don Domenico Grossi with the aim of safeguarding, enhancing, and making more accessible a heritage that was previously scattered across the Marsican churches and often targeted by theft.

[4] Other works, stolen to order, included the cross by Nicola da Guardiagrele, traditionally carried in processions, of which only pieces were recovered, and eight illuminated choir books from the 14th and 15th centuries, of which only two remain intact.

[4] Nicholas the Greek at the base, from the Church of San Francesco]] The Duomo of Guardiagrele has undergone several transformations over the centuries due to troubled historical events, changing tastes, and practical needs that have repeatedly altered its appearance.

The jambs feature clusters of receding columns, with capitals adorned with delicate vegetal motifs and Attic bases, along with concentric cords of the depressed architrave.