5 million years ago: Sea levels drop leaving sand and clay deposits across the Val d'Orcia and the Radicofani and Amiata volcanoes erupt, spreading a dark magma known as trachite – resulting in a soil mixture perfect for growing Sangiovese grapes.
600 BC: Archeological digs confirm that the Etruscans occupied Castiglion del Bosco as far back as 600 BC - prizing its elevated position as a military outlook.
725 AD: The Via Francigena, leading from Canterbury to Rome, is established, and used for centuries by thousands of pilgrims. The road passed through Castiglion del Bosco where pilgrims would shelter in the Pieve San Michele.
1100: Castiglion del Bosco's Castello is built in classic medieval style; its form is similar to that of Rocca of Tentennano, located not far from the Estate. In the early 13th century, the family of Cacciaconti of Trequanda surrounded the hilltop bastion with stone walls. Still standing today are remnants of the walled enclosure, a gate and the partially destroyed Castello.
1208: Castiglion del Bosco holds a prominent position in the Sienese Republic, paying the highest property tax of all the estates.
1313: Badia Ardenga, a handsome abbey located near the Fiume Ombrone, is visited by emperors and popes traveling along the ancient Via Franciegena route. Built before 1000 AD, the original formation is still intact today. According to legend, German Emperor Henry VII of Luxembourg and his army went to the abbey to take communion during their stop in Buonconvento in 1313. Allegedly, the monks poisoned the Eucharist and the emperor was found dead in the church.
1318: Castiglion del Bosco is taken over by the Gallerani family – prosperous merchants who held public offices in Siena. It has been claimed that Cecilia Gallerani, was the subject of Leonardo da Vinci's painting "The Lady with an Ermine" and a muse for the "Mona Lisa".
1339: Upon Ciampolo Gallerani's death, ownership of Castiglion del Bosco passes to the Piccolomini family, who conquered the castle after a long and bloody siege. During this period, the fortification was restored.
1345: Pietro Lorenzetti paints the fresco "Annunciazione dei Santi" in the Church of San Michele in Castiglion del Bosco's Il Borgo. It was rediscovered in 1876 and fully restored to its original glory. Pietro and his brother, Ambrogio Lorenzetti, who painted the Allegory of Good Government and Bad Government fresco in the Palazzo Pubblico in Siena, belonged to the famous Sienese School which flourished during the late Middle Ages and foreshadowed the art of the Renaissance.