An amphitheatre rising between the mountains and the sea.

Rough as its vine-dressers, as peevish as any borderland can be, generous as much as its table and its wines.

The Collio extends from the Judrio river in the west, where it borders the Colli Orientali del Friuli DOC, to the Slovenian border on the east.
To the south, it is bordered by the Isonzo river. The soil of the region is composed of calcareous marl and flysch sandstone.