Semifonte was a fortified city in Tuscany, Italy, built during the late 12th century and destroyed after a siege by Florence in 1202. Its remains are within the modern comune of Barberino Val d'Elsa.
It was sited midway between Florence and Siena on a hill overlooking the Elsa valley and the intersection of the two main routes in the area, the Via Francigena and the Via Chiantigiana, so enabling it to control trade in Tuscany. This dominant position proved to be its downfall.
The peace treaty required the surviving inhabitants to demolish their own city, exiled them all, and forbade any further building on the site. Supposedly salt was plowed into the ground.
Wikipedia https://en.wikipedia.org/wiki/Semifonte
Address SP50, 50021, Italy
Coordinates 43°32'31.658" N 11°7'52.639" E