Already inhabited in Roman times, Altopascio gained in importance due to its Spedale (hostel, first mentioned in 1084) for the pilgrims who travelled on the Via Francigena, leading from France to Rome. This formed the basis of the later Order of Saint James of Altopascio. This, founded by Matilda of Canossa between 1070 and 1080, was one of the first of the Military Orders; it existed for four hundred years, in which it had considerable social, political and military influence, and though gaining land in various European countries retained its strong ties to the town where it was founded.
Badia of St. Peter, known from 1039. It was held by the Benedictines from 1086 and then by the Camaldolese from 1103. It reached its maximum splendour in the later 13th century, but by the Battle of Altopascio (1325) it began to decline, and was abandoned in 1408. Of the medieval original structure, only the exterior of the apse remain.
Church of Santi Jacopo, Cristoforo and Eligio (best known as San Jacopo Maggiore), annexed to the Spedale. It was a medieval hospital complex, of which the cloister, the bell tower and parts (façade and apse area) of the Romanesque church.