Ancient sources handed on the existence of a church dating back to the early middle ages to Castell'Arquato, founded in 758 by the noble Magno, dedicated to Our Lady of the Assumption and in 772 donated to the Bishop of Piacenza. This building was not remains today no trace architectural, while it may be connected to the baptismal font medieval circular still preserved. The Church, from the sources cited as parish in 1059, was seriously damaged by the earthquake of 1117 and therefore quickly rebuilt. The current Collegiate Church of S. Maria Assunta was finished in 1122. Noteworthy are the chapels of St. Catherine of Alexandria, entirely built and frescoed at the beginning of the XV century, and S. Giuseppe, built instead in 1630, which ex vote for the end of the plague and unique heritage of baroque art present inside the church. The Museum of the Collegiate Church is located in the buildings adjacent to the church. It is accessed from the churchyard in front of the facade crossing the cloister dating back to the end of the XIII or at the beginning of the XIV century. Contains works from the Collegiate Church itself and from neighboring churches: silverware and sacred furnishings, paintings, sculptures, furniture, codes and archive material.