The first foundation of the Barga Cathedral, actually the Collegiate Church of San Cristoforo, dates back to before the year 1000, but if it was first enlarged in Romanesque style in the 12th century, then with the insertion of Gothic motifs in the 13th century and finally with the insertion of the two large side chapels and the choir between the 16th and 17th centuries. The current façade, which was actually one of the sides of the original church, is very suggestive both for the particular "Alberese di Barga" stones which change shades and shades depending on the light, and for the exceptional view that can be enjoyed from this place on the top of the town with the Tuscan-Emilian Apennines behind it and in front the Serchio valley and the Apuan Alps in the background. On the side door there is a bas-relief attributed to the sculptor Biduino (12th century) which depicts the miracle of the "Scifo d'Oro" of Saint Nicholas, while the interior houses a wonderful marble pulpit attributed to Guido Bigarelli da Como (13th century), where scenes of the nativity of Christ are sculpted, and the Ciborium of the Holy Oils, a terracotta attributed to Andrea Della Robbia.
The Bell Tower houses three bells which are still rung manually.
The collegiate church of San Cristoforo is the main place of Catholic worship in Barga, in the province of Lucca, the seat of the parish of the same name that is part of the pastoral unit of the same name in the archdiocese of Pisa.