The Church of Saints Pietro and Paolo (Basilica dei Santi Pietro e Paolo), also known as the Pieve Church (Basilica di Pieve), is the oldest religious building in Guastalla and in the entire province of Reggio Emilia. Its original structure, dating back to before the 10th century, is dedicated to the Apostles Saint Peter and Saint Paul.

Archival records attest to its consecration in 997 by Pope Gregory V. The church gained historical prominence as the seat of a synod convened in 1095 by Pope Urban II, a key figure of the First Crusade, and later in 1106 as the venue for a Council led by Pope Paschal II during the Investiture Controversy. Across more than a millennium of history, the church has undergone multiple transformations, culminating in 1931, after the dramatic collapse of its ceiling prompted extensive restoration. These works restored much of the church’s evocative splendour and revealed early Roman artefacts, including bricks and tiles, still visible today in the inner and outer perimeter walls. Moreover, inside, the church also preserves an organ from 1870, which incorporates 17th-century-pipes from its predecessor.