The original core of the building dates back to the first half of year 1000, but it was only after 1100, upon request of bishop Aldo, that the temple found its definitive setting as church and annexed monastery. Like many other churches in Piacenza, also Santa Eufemia shows the coexistence in a single building of different structures superimposed one to the other in different periods. 

After 1100 a portico was added, supported by pillars decorated with precious Romanesque capitals. In the 12th century it was raised to the level of the façade. The main renovation works of the original structure date back to the 18th century: the gate on the façade was adapted to the Baroque style, in the perimeter walls were created several chapels, the bell tower was demolished – for reasons related to statics – and rebuilt only in the 19th century. 

On the inside there are three naves with apses separated by pillars, terracotta decoration dominates the whole church. According to tradition, bishop Aldo wished to be buried here, but his relics were never found, but Santa Eufemia relics were excavated instead. The church also preserves a mosaic from the 12th century depicting Saint George.