The most ancient and most important architectural work in the town of Filattiera is the parish of Santo Stefano in Sorano. This millenary building, founded by the Lombards, is set in a valley bottom, where there are the roads thanks to which the village became famous: the Cisa way (the prehistoric cisalpine way), the Aemilia-Scauri way, a Roman track, and the Francigena way.

The first document about the parish of Sorano dates to 1148. It is a Papal bull that confirms its possession to the Bishop of Luni. It can be inferred that the parish was already a well-consolidated structure in the XII century.
The Parish of Santo Stefano was built with stones and cobbled paving coming from the banks of the nearby Magra stream and it was a very powerful religious centre for a long time. In the centuries, it accumulated enormous wealth and opened numerous affiliates in the valley crossed by the river. One of them was built right in Filattiera. The centre of Sorano started to be totally depopulated since the XVIII century and the parish became isolated.
Its X-century Romanesque layout, therefore, has remained unchanged and its apse and its squat belfry, which was probably used on a defensive purpose, are still kept, too. Its inside, instead, has been changed and only recent restorations have revealed the ancient Medieval decorative frescoes under the plasterwork and some sculptures. A perfectly preserved pre-Christian idol is also kept in the church.
The area of Sorano had not been inhabited for centuries, but it was certainly settled in Prehistory, since it is near the ancient road of the Val di Magra that hunters used during their long battues. Archaeological excavations have defined the story of human presence here before the Parish was built. In effect, many stelae-statues have been found near Sorano. They are carved stones that confirm the presence of quite important settlements here since the Bronze Age. More recently, further research works have led to the discovery of an ancient Roman "castrum" dating to the I century B.C. that was later transformed into a "mansion", a farm-inn. The decay of this area probably dates to 540 A.D.