The Sestaione Valley is located on the Tuscan-Emilian Apennines, in the northern part of the Province of Pistoia and is crossed by the Sestaione stream, a tributary of the La Lima stream, which is a tributary of the Serchio river, which flows into the Tyrrhenian Sea. From its head, to the west, near the Alpe Tre Potenze, a mountain 1940 meters high asl, until the mouth of the Lima Valley, the Valle del Sestaione has first run from south-west to north-east, for about a third of the its length, therefore from North-West to South-East. Its left side, detaching to the west from the Alpe Tre Potenze, on the border with Lucca, is bordered to the north: from Passo della Vecchia, from Monte Dente della Vecchia, from Passo della Fariola, from the massive Mount Gomito, 1892 meters high above sea level, then from the long ridge that descends through the Selletta to the confluence of the Sestaione stream in the La Lima stream. Its right side, after being detached, to the west, from the Alpe Tre Potenze, continues through the Foce di Campolino and Monte Poggione, then descending through the mountain Uccelliera and the Passo della Sentinella up to Monte Caligi. To the east the Valle del Sestaione flows into the Pistoia area of ​​the Lima Valley, almost opposite the town of Cutigliano. Towards the North the Valle del Sestaione borders first with the Val di Luce, then with the Valley of the Scoltenna stream, a tributary of the Panaro river, a tributary of the Po river, which flows into the Adriatic Sea. Towards the south, the Valle del Sestaione borders first with the Lucca Valley of the Fegana, then with the middle course, in the territory of Lucca, of the Valley of the La Lima stream, a tributary of the Serchio river, which flows into the Tyrrhenian Sea. In the western part, the territory of the Valle del Sestaione belongs to the Municipality of Abetone; in the eastern part, where there are the inhabited centers of Pian di Novello and Piano degli Ontani, in the Municipality of Cutigliano. From the Alpe Tre Potenze to the outlet in the Lima Valley, in front of the town of Cutigliano, at 637 meters above sea level, the Sestaione Valley has a length of about 10 km and a height difference of 1303 meters. Below the average altitude of about 1550 meters s.l.m. the Valle del Sestaione is covered by a thick arboreal and shrubby vegetation: the predominant forest essences are the beech and the spruce; in addition, the vegetation is represented by high altitude moors, with frequent vaccines and outcropping rocks. Around the villages of Piano degli Ontani and Pian di Novello there are fields and meadows.