The Furlo Pass is a gorge on the ancient Roman road Via Flaminia. The tunnel dates from the time of emperor Vespasian (69–79AD) so that there was more space at the narrowest point of the gorge. In the 1980s a larger tunnel was constructed on the nearby motorway, so now the Furlo Pass is quiet.

Source and more info: en.wikipedia.org/wiki/Furlo_Pass