The Church of the Ss. Stefano and Andrea is in the upper part of Marciano della Chiana. It rises near the fortress and it was built with the material taken from part of the castle walls that have been pulled down to leave room to the building.

The parish of San Pietro in Agello, which is in the Northwestern part of the territory and the today is part of the structure of a farm-house, was the most important church of Marciano in the origins.
Since the X century, the population felt the need to shift the font in Marciano, which was becoming more and more important. The baptistery also had a high symbolic value besides its religious one (baptism was received in it). The parish that had it also controlled the other churches of the area.
The parish of Santo Stefano, therefore, became the main religious centre in Marciano. At the end of the XVI century, the church also became the seat of investiture of the chevaliers of the "Ordine di Santo Stefano". Therefore, the works of enlargement that used part of the Medici's financing in the ambit of the reorganization of Marciano began. The works finished in 1592.
A plaque to the let of the main entrance recalls the date of consecration of the church carried out by the bishop of Arezzo in 1750, even if this place had been opened to the population since when the works had finished. On the outside, a small red-bricked parsonage can be seen and, according to some researchers, it could have been the old chapel of the Palazzo dei Priori. The church required another huge restoration work in the postwar period after the damage caused by bombardments. The works finished in 1980 and the building recovered its ancient splendour thanks to them.
The inside has one nave and two aisles supported by twelve columns and with two staircases that lead to the apse. There are seven altars inside the church (the main one has been carried here from the monastery of Santa Maria delle Vertighe to substitute the one destroyed in 1944), plus, three more in each side. Among the main works decorating them, there is a highly valuable painting, the "Madonna con ai piedi San Fabiano e San Sebastiano inginocchiati", by Vasari of the XVI century.