The strategic importance of Magliano, so close to the sea and the hinterland from Amiata to Pitigliano, has always been undoubted. Today the city walls of Magliano in Toscana is one of the most interesting and complete medieval urban fortifications in Tuscany, both for the scenic aspect and for the high example of military architecture that they represent. On the hill where the town stands there was a castle, named for the first time in 1097 and included in all the acts of division of the territories of the Aldobrandeschi, Counts of Santa Fiora and lords of the area.
In 1326 Magliano was occupied by the King of Naples and granted by Carlo, Duke of Calabria and head of the imperial forces, to the Counts of Pannocchieschi but after only a year, thanks to the intervention of Ludovico il Bavaro, it was returned to the Counts of Santa Fiora. Before leaving the castle, the Pannocchieschi set it on fire. In 1358 the toll was granted on emphyteusis to the Republic of Siena who granted it in lordship to Spinello di Spinello Tolomei. The Sienese immediately took care of rebuilding the Cassero, now disappeared, and in the following twenty years, with the use of skilled workers, to reinforce the walls. Further additions and improvements were made during the XV Century.
 Of the latter still today three sides are well preserved, interspersed with round towers and square towers, remains of the castle, perfect fusion between pre-existing Aldobrandesche and late medieval Sienese additions. The walkway, recently restored and largely accessible, is supported by hanging arches on inverted pyramid shelves, a classic of Sienese fortified architecture. The north side is now incorporated into the houses and difficult to read. The Porta San Giovanni on the south side and that of San Martino on the north side are the two, still intact, original entrances to the enclosure.