The Valley of the Flour Mill is a narrow and deep historic valley in the middle of the city, which is worth a look.

The valley itself was formed about 37,000 years ago by water seeping from the eruption of Campi Flegrei, which reached this area and penetrated the tuff rocks here.

The building standing in the middle of the valley, now covered with vegetation, was once a water station that used river water to operate a wheat-grain grinding mill and a sawmill that provided wood from cherry, olive, and walnut trees for local artisans and house construction.

At night, the valley is illuminated and looks impressive.