As the name suggests, the parish of St. Cecilia a Decimo [1, 2, 3] rises by the tenth mile from Florence on the current Via Cassia, an important way of roman origin. Here, in antiquity, rose a staging post and the roman presence is witnessed also by a funerary stele conserved inside the parish . A document of 884 refers to the building that existed before the present one, which refers stylistically to XI century, when it was competence of the Earls of Monte Rinaldi. The parish, which led a wide area, was submitted all the same to the authority of the Republic and of the Bishops of Florence, who were the owners of the castle of Decimo and of many surrounding buildings and lands.
The constant development of the village of San Cassiano, arisen around a church suffragan of St. Cecilia, diminished progressively the importance of the parish, mostly after 1354, when Florence gave the village a circle of defensive walls, which did not include the parish. This, after a slow period of decadence, was deprived in 1797 of the title of parish in favour of the church of San Cassiano, already elected Rectory [5-6].
The parish of Decimo preserves the original roman basilican plan with three naves, separated by arches on pillars. However, the ancient structures are hidden from the outside by a building leant against the church and from the inside by plasters and stuccos, result of 18th century readjustments. The regular purse, which ends the central nave and the façade porch is not part of the original version. The huge bell tower, with a massive structure and without openings until the top, preserves its ancient characteristics instead, although damaged by the earthquake of 1895. To the South of the church there is the cloister, whose structures are still recognizable, though the arches have been buffered , while on the northern side leans the oratory of the Company of Sacrament.
Inside the parish are conserved many paintings, amongst them a fragment of fresco by Cenni di Francesco with the Madonna with the Infant (end XIV – beginning XV century)  and the wonderful 16th century board by Michele di Ridolfo del Ghirlandaio with the Madonna with the Infant and the Saints Lawrence and Cecilia, recently restored . Beyond the other three 17th century paintings, it is to remember the presence by the altar that ends the small right nave, of a silver reliquary of the XVII century with the form of an arm, containing a relic of the titular saint.