Stia is a frazione of the comune of Pratovecchio Stia in the Province of Arezzo in the Italian region Tuscany, located about 40 kilometres (25 mi) east of Florence and about 40 kilometres (25 mi) northwest of Arezzo. It was an independent commune until it was merged to Pratovecchio in 2014.
The town of Stia is often called the "source of the Arno", although the real source is some 1,200 metres (3,900 ft) higher on the slopes of Monte Falterona. However Stia is the first true village the Arno reaches, where it is joined by another river, the Staggia, that starts at Passo la Calla to the north-east. It is suggested that the name 'Stia' comes from a corruption of the river Staggia's name. As well as the being situated on the confluence of the Arno and the Staggia, Stia also has its own spring that rises in the park of Palagio Fiorentino, which has now been channelled so the water flows from 10 permanent taps.
Stia borders the following municipalities: Londa, Pratovecchio, San Godenzo and Santa Sofia. It contus the hamlets (frazioni) of Molin di Bucchio, Palazzo, Papiano, Papiano Alto, Porciano, Santa Maria alle Grazie and Vallucciole.
Stia grew up as the market place below the Guidi castle at Porciano. Presumably due to the topography, the piazza is not a normal square, but a more unusual triangular shape, sloping steeply at its far end. Today called Piazza Tanucci, after the Bernardo Tanucci, an Italian statesman, who was born in Stia in 1698.
Stia boasts a pair of covered arcades that run along either side of the piazza, today housing a variety of shops, bars and restaurants. On entering the piazza from the lower end, the baroque facade of Santa Maria della Assunta dominates the left-hand side of the street. The plain, 19th-century facade belies the fact that inside is a well-preserved Romanesque interior that is at least six hundred years older.