The name Trecciano is of Latin origin, perhaps it is the name of a person: Triccius. The first records of the hamlet date back to the twelfth century, when Count Bernardino gave the rectory of S. Maria of Siena many of his possessions, including a farm estate in Trecciano held by the sons of Paganello Baciabotte. In a document of 1179, Pope Alexander III, mentions for the first time the rectory of S. Michele in Trecciano, assigning the property to the Abbey of Torri. In the twelfth and thirteenth century Trecciano was the site of a small village of the countryside near Siena until 1366, when it was connected to the more populous village of Sovicille. The building of the rectory, which has preserved its original character, has a nave and transept with three apses. Along the right wall we see the small bell tower similar to that of the parish church of Ponte allo Spino. Higher, on the road, there is a stone house that shows remarkable medieval structures of a very primitive character.