Vallone dei Mulini in Sorrento is a place of great naturalistic suggestion and owes its origin to the most violent eruption in the history of the Phlegrean Fields and to the subsequent processes of erosion by the waters that progressively engraved the tufa basement. The formation of this deep fissure in the rock dates back to about 35,000 years ago. The Vallone dei Mulini is the best preserved valley in the Peninsula (there are four others), even if today, unfortunately, it is possible to admire only the central part that extends from Piazza Tasso to the villa La Rupe and from here to the Porta degli Anastasi. The Vallone owes its name to the presence of a mill, of which the ruins are visible, used until the beginning of the 20th century to grind wheat. In addition to the mill, historical and artistic evidence also tell the presence of a sawmill and a public washhouse. The construction of Piazza Tasso (1866) decreed the end of activities in the valley. The filling of the end of the valley with the consequent isolation of the area from the sea, causò a sharp rise in the rate of humidityà that made unlivable the’area. The particular microclimate favorì instead, the development of a luxuriant herbaceous and tree vegetation.