The complex of Santo Stefano is composed of an ensemble of chapels, churches and associated monastery, known together as the “Sette Chiese” (seven churches). According to a legend, Santo Stefano was founded by San Petronio, the Bishop of Bologna between 431/432 and 450, who is buried there. The story reports that following a pilgrimage in the Holy Land, he founded a group of buildings destined to reproduce the sites of Christ’s Passion. Despite the legend, the first written record of the complex is not until the 9th century, in a diploma of Charles the Fat.
The various components of the complex date to different epochs. The church dedicated to the Holy Sepulcher was possibly a Roman temple dedicated to Isis, later transformed into a church with an edicola inside containing the relics of San Petronio. Where today the church of the Trinity is found, at the end of the 4th century was the area of a walled Christian cemetery. The church of San Giovanni Battista (today called the Crocifisso (crucifix), is instead probably of Lombard foundation, as the so-called basin of Pilate would attest, which contains an inscription referencing Kings Liutprand and Hildebrand, who reigned together from 736 to 744.
The beginning of the 11th century was a moment of great splendor for the complex, when the Abbot Martino built a crypt in the church of San Giovanni Battista, and on March 3, 1019 he translated the bodies of Saints Vitale and Agricola. At that date, the monastery probably already contained the structures that exist today: the curch of San Giovanni, the church dedicated today to Saints Vitale and Agricola, and the church of the Trinity.