According to legend the monastery was built at Charlemagne’s request in around the year 780, although Benedictine monks were probably already present at Sant’Antimo at that time. The abbey grew up as an imperial votive offering and became rich through privileges conceded by emperors and popes: in fact the abbot of Sant’Antimo was granted the title of Count Palatine. Towards the year 1000 the abbey had become a territorial power, its estate extending between Lucca and Orbetello. In 1118, thanks to a large donation made by Count Bernardo degli Ardengheschi, the monks were able to build a new church of grander and more elegant forms. The vast complex extended on the south-facing side, with its cloister, chapterhouse and other rooms for monastic life. An abbey of such dimensions could not escape the ambitious intentions of the commune of Siena, at that time in full expansion.

When Sienese troops attacked Montalcino in 1200, they inevitably sparked the abbey’s decline, although Saint Catherine tried to bring back a wave of spiritual renewal in 1377. It was the Sienese Pius II who decided to suppress the abbey in 1462, despite attempts at reform by the Guglielmiti monks. The church consists of a nave and side aisles with Romanesque style round arches (12th century). It was inspired by French models, with a soaring, light-filled nave. The wide ambulatory can be followed around the apse, just as it was by medieval pilgrims; it is embellished by three small radial chapels. However, the Italian and French masters expressed the best of their art in the church and ambulatory capitals. The capital of the second column on the right is noteworthy, attributed to the famous “Master of Cabestany”. It portrays Daniel in the Lions’ Den. Behind the main altar is a wooden carved and painted Crucifix from around 1250, of local origin. The wooden statue of the Madonna and Child “Sedes Sapientiae” is instead from the Umbrian school (ca. 1260). The feast day of the Madonna of Sant’Antimo takes place on 11 May every year. It is preceded on the evening of the 10th by a solemn and striking procession that starts from Castelnuovo. The crypt contains an altar whose table was recuperated from a tomb stone of Roman origin (350 AD). The ambulatory features two 15th-century frescoes showing Saint Sebastian and a Holy Pope. Since 1992 the church has been given new life thanks to a comunity of canons who follow the rule of St Augustine. They ensure a church service seven times a day and have restored Gregorian chants to the church as they were seven hundred years ago.