Built in the course of the 19th century and sited on the right bank of the Rosaro stream, the Old Arlia Mill is a specimen of the water-powered mills of Lunigiana once used to grind chestnuts, wheat, maize and the minor cereals cultivated in the underlying valley. The Lunigiana Mountain Community sees to restoring the structure by now reduced to ruins, also reviving its old milling activity.

This water-powered mill with a horizontal wheel consists of three stone millstones (one for chestnuts, one for wheat and one for maize), a shelter for the mules that were used as means of transportation to carry the sacks along tracks, and a warehouse. The former warehouse today houses a permanent exhibition with explanatory panels on the history of Lunigiana mills, such as those in Filattiera and Signano di Fivizzano.