Built upon the initiative of a group of citizens who wished to preserve the church during the first centuries of the 17th century (1522-1528), Santa Maria di Campagna was erected on an area previously occupied by another holy building – the sanctuary of Santa Maria di Campagnola – where the people worshipped an image of Virgin with Child from the 14th century. 

According to tradition, Pope Urbano II in 1095 here announced his intention to begin the First Crusade in the Holy Land. The architect Alessio Tramello from Piacenza designed and supervised the project. This central-plan church follows a scheme that was particularly diffused at the time: the harmonious organisation of spaces and volumes, essential and well balanced; an organisation that was to be changed at the end of the 18th century with structural renovations prolonged one of the naves to create the choir and the presbytery we see today. 

The decorations are excellent, as well as the frescoes that cover the walls. Among the artists who worked here there is Antonio Sacchi called Pordenone: he painted Saint Augustine on the entrance wall, also the Magi chapel, and the Saint Catherine chapel. Out of the chapel in the adjacent nave there are works by Camillo Procaccini and Gaspare Traversi. In the sacristy there are canvases by Gaspare Landi and Giulio Campi; the Sant’Antonio chapel presents works by Pietro Antonio Avanzini, Camillo Procaccini and the Bibiena brothers; in the right arm of the cross worked artists like Alessandro Tiarini, Antonio Triva, and Ignazio Stern; the Santa Vittoria Martire chapel was decorated by Ferrante Moreschi, Bernardino Gatti (Saint George killing the dragon), Paolo Bozzini, Ludovico Pesci, and Daniele Crespi. 
All these masterpieces are dominated by the majestic dome on the intersection of the arms of the central plan: in the lantern there is the Holy Father supported by a flock of angels from which other people in Christian history emerge; all frescoes were painted by Pordenone and Sojaro. 

The floor is in multicolor marble, designed by the Milanese artist Giambattista Carrà (1595). Another interesting piece is the statue of Ranuccio I Farnese by the hand of Francesco Mochi (1616).