The Collegiate Church of Santa Maria Assunta is the main religious building in Casole d’Elsa and one of the most emblematic sites in the village’s history. Its origins date back to the 11th century, when the original church was built within the castle of Casole, in a strategic position along one of the routes of the Via Maremmana. This setting immediately enhanced its prestige, reinforced by its connection to the Bishop of Volterra, who used the village as a strategic outpost for controlling the territory.

The first documentary record dates back to the years between 1039 and 1046, when it is mentioned as ‘ecclesia Sanctae Mariae in castello quod dicitur Casule’. By the 12th century, the church already had a cloister, a sign of its importance not only in religious but also in civil terms: it was here, in fact, that the most significant public documents relating to the life of the castle were drawn up. During the 14th century, the collegiate church further consolidated its role, becoming the seat of the diocesan vicar for the Valdelsa and benefiting from substantial revenues. During this period, the side chapels were enriched by local families and confraternities, such as the Compagnia della Santa Croce.

From an architectural point of view, the building has undergone significant changes. Originally, it was a three-nave basilica with an apse and a wooden roof, featuring three apses, in a style typical of Tuscan Romanesque architecture. Today it features a gabled façade, embellished with decorative elements reminiscent of the Volterra style, including half-columns with carved capitals and an elegant architraved portal surmounted by a monolithic lunette decorated with plant and geometric motifs.

The bell tower, imposing and austere, stands out for its compact structure and few openings, which accentuate its defensive appearance. Inside, the ancient three-nave layout has been transformed over time into a single-nave space with a roof of exposed wooden beams. The 14th-century transept, connected to the original structure by a large pointed arch, leads into the choir area, flanked by side chapels that enrich the overall architectural ensemble.

Over the centuries, the collegiate church has undergone significant alterations, such as the removal and reconstruction of the crypt, originally situated beneath the chancel, which no longer exists in its original form. Despite these transformations, the building retains the charm of a long historical legacy, in which religious, civil and artistic functions are intertwined.

The Collegiate Church of Santa Maria Assunta remains the spiritual heart of Casole d’Elsa to this day, a place that tells the story of over a thousand years of history and bears witness to the village’s importance in medieval Tuscany.