Nothing is left of the structure of the San Girolamo Oratory, built in the first half of the 1600's, and its Baroque frescoes of the Bologna School were also totally destroyed by bombing during the last war. The two small chapels to the sides of the entrance have survived however, linking the San Giovannino Oratory to its twin structure. The complex was built in 1782 to designs by Gaetano Stagnani, on the site occupied since the 13th century by the church of San Giovanni degli Armeni, purchased in 1442 by the Confraternity of San Girolamo.

In the San Giovannino Oratory there are several objects from the 18th-century church, including several small paintings showing episodes from the life of St Jerome done by Cesare Pronti around 1687, and a painting showing the Virgin Mary with St John and St Jerome, by Giovan Battista Costa and dated 1738. There is also an elegant 15th-century stoup from the Florentine workshop of Antonio Rossellino, with a pilastered column supporting a basin in the form of a small ship, in turn surmounted by bronze statue of St Jerome.

The large altarpiece showing St Jerome in the Desert that hung above the main altar of the San Girolamo Oratory is now on display at the Civic Museum, where it was consigned for safekeeping by the Confraternity. Painted in 1641, it is one of the most significant works of Guercino's maturity, a masterpiece commissioned by the Theatine friar Tommaso da Carpegna, a collector of Guercino's works.