The church of S. Giuseppe, originally dedicated to SS. Cosima and Damiano, is, according to tradition, one of the earliest in the town. In fact, it is said to have been founded by Crispin II (6th century) or by Damian (7th-8th century), both bishops of Pavia. In the Middle Ages it was also known as S. Damianino due to its small size. Documents relating to pastoral visits reveal that in the 15th century it had a very low income and was partly occupied “per laycum”. In 1566 (on the orders of cardinal Ippolito de’ Rossi) the church was closed and put up for sale with its outbuildings. The complex was bought by the Guild of Builders and Carpenters which, after having restored it, established itself there, dedicating the building to S. Giuseppe. In 1639 its reconstruction began in the present form (single nave with four side chapels) with an increase in size. It was deconsecrated at the beginning of the 19th century and turned into a timber warehouse. In more recent times it was used as for commercial activities.

During work for its conversion into a house, several structures emerged together with an archaeological stratigraphy in which there are five phases. The earliest three indicate a residential use of the area. No structures emerged that prove the construction of the church in a very early period, however, it cannot be excluded that a church stood nearby. Moreover the sources mention a small church.

The discovery of residential type structures probably of late medieval date was of great interest. They seem to confirm the literary evidence indicating the poverty of the parish and the occupation of the space for lay purposes.

Lastly, the excavation proved that the church was substantially rebuilt in the 17th century: the type of walls and burials correspond to those in use in that period.