Located south-east of the Collegiate Church, the oratory of Corpus Christi is a rectangular building obtained from a patrician house transformed into a place of worship in the sixteenth century. Above the portal is a fragment of a 17th century fresco depicting the Adoration of the Blessed Sacrament.
Inside the nave is divided into three bays with barrel vault lunettes. The rich and valuable polychrome stucco decoration is the work of Domenico Pacciorini of Ravecchia (1640); noteworthy is the scene of the Annunciation in the lunette. The paintings of the Last Supper and the Coronation of the Virgin date back to the first half of the seventeenth century and are the work of Salvatore Pozzi di Valsolda. Of another hand and very interesting are the representations of Eucharistic subject located in the side lunettes (seventeenth century). The Baroque marble altar dates back to about 1770.