Allein is a town and comune in the Aosta Valley region of northwestern Italy. It is one of the small municipalities that make up this mountainous, bilingual region, which borders France and Switzerland and is Italy's smallest region by area.
The comune is located in the Alpine terrain of the Aosta Valley, a predominantly mountainous area traversed by the Dora Baltea river and surrounded by some of the highest peaks in the Alps. Like other settlements in the region, Allein is a small community within a landscape shaped by valley geography and mountain passes.
The Aosta Valley is officially bilingual in Italian and French, and its place names commonly appear in both languages. Allein shares in this regional character as a minor comune within the valley's administrative structure.