The monastery structure is formed with the Church, the Monastery and the  San Giovanni Old pharmacy.
The church  was built for the Benedectine order between 1498 and 1510 but its elaborate white marble Baroque facade contrasts with the Renaissance architecture of the cloisters and convent.
In the Latin-cross interior, a frieze running along the nave was painted in 1522-23 by Correggio, who also decorated with grotesques the nave columns, the entrance to the 5th north chapel and the famous fresco cycle in the dome, traditionally referred to as the Vision of St. John at Patmos, an uncommon subject in Christian iconography. The evangelist is depicted as an old man gazing up at the sky, while the central figure of Christ is moving towards him. Light, colors and the shape of clouds on which the apostles are seated give an illusion of great depth, freedom and dynamism. Behind the 17th century altar in polychrome marble is a large canvas of the Transfiguration by Girolamo Mazzola-Bedoli, who also painted the Mystic Marriage of St. Catherine in the 4th north chapel (1536). A wooden choir by Marcantonio Zucchi, inlaid with floral motifs, views of towns and hills and musical instruments, runs around the apse. 
To be noticed is also a putto under the tower between the north pendentives, recently attributed to Parmigianino, as well as his frescoes in the north aisle with figures of saints.
On the left of the church entrance is the Benedectine monastery, a huge complex with a chapter-house, a refectory and elegant Renaissance cloisters: St. John Cloister (1537), the Chapter Cloister (1500) with a marble portal and the Large of St. Benedict Cloister. Frescoes by Correggio in the chapter-house show the Christian Sacrifice. In the monastery is housed a 16th century library with frescoed walls and a collection of 20.000 books and rare codices.