The Opera Museum is included in the Opa Si Pass which also includes the Cathedral and its pavement, the Piccolomini Library, the Crypt, the Baptistery, the Oratory of St Bernardino.
Established in 1869 in the right nave of the New Cathedral, the Opera del Duomo Museum is spread over three floors and houses a rich and varied collection of works.
The visit begins from the ground floor hall dominated by the imposing 13th-century stained glass by Duccio di Buoninsegna, a triumph of colors representing the Stories of the Virgin; in this room there are important 14th century sculptural works from the Cathedral's facade as the Sibyls and Prophets made by Giovanni Pisano, as well as the famous 15th-century Tondo with the Madonna del Perdono by Donatello.
On the first floor we find the Duccio di Buoninsegna room, where the protagonist is his wonderful painting of the Majesty, alongside the Nativity of the Virgin by Pietro Lorenzetti; continuing we find the Sala del Tesoro, which houses furnishings of the sacred liturgy, among which stand out the San Galgano Reliquary and the Reliquary of the St John's Arm. Of great interest and elegance is also the liturgical service made of rock crystal, which demonstrate the sophistication and quality of the Sienese goldsmith.
On the second floor there is the Room of panel painting with the famous Virgin of big eyes realized by the Master of Tressa, the Alfieri's Room with works by Domenico Beccafumi and Luca Giordano, and finally the Hall of Tapestries.