The town was a feud of the Lombard Rolandinghi family in the 11th century, but after it came under the rule of the Marquisate of Toscana, it came into conflict with the nearby city of Lucca round about 1000.

After Garfagnana was conquered by Lucca, it was divided into three areas: Castiglione, Coreglia and Barga, which became an important trade exchange centre. In 1298 the inhabitants of Lucca besieged Barga, pulling down its circle of walls, and till the death of Castruccio Castracani in 1328 the town remained under the rule of Lucca. After a lot of events, Barga decided freely in 1340 to come under the protection of Florence and it remained under its rule till 1847, when it became a vicariate of Lucca. Not to forget is the participation of Antonio Mordini in the wars of independence under the leadership of Giuseppe Garibaldi.

From the 19th century on the inhabitants of Barga began to emigrate to Scotland, to America and to Australia. The Cathedral of Barga, built at various times, dates from round about 1000, but it was enlarged and given a Romanesque appearance in the 12th century.

Two centuries later a second change was introduced. Between the 16th and the 17th century the Cathedral was given its current appearance with the construction of the two chapels and the choir. The main entrance (flanked by two lions' statues resting on two columns) is embellished by an arch with carved acanthus leaves and a lintel with bas-relieves, depicting a scene from the vintage time. The entrance of the Cathedral, dating back to 9th century, leads us inside a three-naves church with an inlaid white marble baptismal font on the right. The pulpit is decorated with bas-relieves and propped up by Corinthian columns, except for a Middle Ages one. In one of the niches there is a wooden statue, depicting S. Cristoforo (to whom the church is consecrated) with the Infant Jesus on a shoulder helping him to cross the river.