Altstätten is a small historic rural town and a municipality in the district Rhine Valley, in the canton of St. Gall in Switzerland. It is located with some secure distance of about 5 kilometres (3.1 mi) west from the Alpine Rhine in the flat and wide St. Gall Rhine Valley, which also designates the border with Austria. It further gives access to the higher situated Appenzell to the west.

The canton of St. Gallen or St Gall is a canton of Switzerland. Its capital is St. Gallen.