Valtellina is a high Alpine valley in Lombardy, its terraces climbing the steep south-facing slopes above the River Adda beneath the Rhaetian Alps. Around 2,500 kilometres of dry-stone walls support vineyards so steep that every task is still done by hand, a scale of manual viticulture with few parallels anywhere. Nebbiolo, known here as Chiavennasca, accounts for over 90% of plantings, making Valtellina the second-largest source of Nebbiolo in the world, producing wines leaner and more mineral than their counterparts in Piedmont. Sforzato di Valtellina, made from grapes dried after harvest, is a dry, concentrated speciality unique to the valley. Switzerland governed Valtellina for nearly three centuries from 1512, a period that shaped both the valley's wine trade and its export-driven training methods.