The church of Sant’Alessandro stands in the centre of Vecchiano. Also called Sant’Alessandro a Vecchiano maggiore, to distinguish it from San Frediano a Vecchiano minore, the church has known two different construction phases: the first, referable to a smaller building and recognisable in the two single-lancet windows on the left side, would date back to the 11th century, while the second, testified by the two closed arches on the same side, would be referable to the late 12th and early 13th century. The main gabled façade has no parvis and faces directly onto Via Sant’Alessandro. It presents the main entrance portal with a cornice in pietra serena (grey stone) and accompanied by two rectangular windows in the upper part. The façade on Piazza Garibaldi is characterised by a continuous wall face: the lower part is made of squared limestone ashlars. The opposite façade is made of light limestone ashlars and characterised by the presence of two round arches.
Opposite the church, on the opposite side of the street, stands the solid bell tower, begun in the mid-12th century and completed in 1385, as attested by the marble epigraph. The square-based tower is embellished at the top with elegant mullioned and three-light windows and robust battlements. Internally, the church has a single nave covered by a wooden truss roof and closed by a semicircular apse decorated with wall paintings. It houses two 18th-century stoups and a pair of capitals from the 12th-13th centuries.