Adjacent, and just north of the province of Verona, is the province of Trento. Located here is the hardest climb in Italy and perhaps Europe. The Scanuppia Malga Palazzo climb is 8km long, starting from Besenello and ending at a nature preserve.
Most of the ride reports I've read about involve stopping and starting repeatedly to get up; weaving back and forth is close to impossible because of the narrowness of the paved road. One person that did make it up without stopping, and with great difficulty, used a 22 (front) x 28 (rear) gear combination!
I hope to pay a visit this Spring or Summer but like so many others I think I'll be walking a bit.
A great website for researching climbs and their difficulty rating is http://www.salite.ch/