La leggenda narra che Carlo Magno, attorno all’anno 800, returning to Rome, camped his men, struck by the plague, in the vicinity of Starch. On the night in a dream an angel appeared to the Emperor who advised him to pick a particular grass, dry and then make an infusion with some wine drinking by making the soldiers. This was done and the army recovered. Charlemagne, whose name was linked to the herb known as "Carolina" in thanksgiving for the miracle he had built the Abbey giving the bones of saints and martyrs Antimo Sebastian. Abbey, built as a votive Imperial, was protected and enriched by the privileges granted by the descendants of Charlemagne, abbot of Saint Antimo was in fact also attributed the important title of Count Palatine. The abbey to the Mille was already a potentate and its territorial possessions, scattered between Lucca and Orbetello, monasteries counted nine, forty-six churches and Seventeen different castles, mills and farms.
In 1118, thanks to a magnificent donation of Count Bernardo Ardengheschi, the monks were able to rebuild their church in a more grand and elegant.
The new building was built inspired by French models, with the central nave soaring and bright, with forums, enriched by imaginative sculptures of French masters. On the side facing south stretched the rest of the vast complex, with its cloister, chapter house, scriptorium and other environments for the monastic life.
When in 1200 the Sienese troops led by Filippo Montalcino Malavolti attacked, they were right even of soldiers sent by the abbot of Sant 'Antimo. Consequence of defeat was passed on to Siena for a good part of the estate and thus began, inexorable decline.
Ascended to the papal throne, in 1462 the Sienese Pope Pius II decided that the suppression of the Abbey falls increasingly abandonment, both materially and spiritually.
