The church was founded (over the remains of a Roman bath building) around the year 654 at the behest of Gundeberga, wife of Rothari and Arioald and daughter of Queen Theodelinda and Agilulf to accommodate her burial or to be the seat of the spring.

[2] Between the ninth and tenth centuries a copious series of imperial diplomas were issued for the church, in which the foundation of Gundiperga is mentioned, while in an act of the bishop of Pavia Bernard I of 1129 the "pro anima" masses of Queen Gundeberga are attested.

[5] Immediately on the right there is a part of the ancient baptistery annexed to the church, and in the first chapel, also on the right, there is an altarpiece, painted by the Milanese Giovan Battista Sassi, which depicts Saint Andrew Avellino dying in front of the altar.

The frescoes (dated to the 12th century) mostly portray local saints; there is a scene from the life of John the Baptist, very compromised.

The discovery of the crypt, which had been buried for centuries and reduced to a burial ground, took place on April 18, 1914, thanks to the initiative of Monsignor Faustino Gianani who, following the indications of many historical sources, had a tunnel dug in the courtyard behind.