Mortirolo Pass

The Mortirolo Pass is a high mountain pass in the Alps in Italy. Also known as Passo della Foppa, it connects Mazzo di Valtellina and Val Camonica. The road from Mazzo di Valtellina is one of the most demanding climbs in professional road bicycle racing, having been used in the Giro d'Italia stage race many times.

In May 2004, while training in Italian Alps, Lance Armstrong said that it was the hardest climb he had ever ridden.

Source: Wikipedia