Raetia (so always in inscriptions; classical manuscripts usually use the form Rhaetia) was a province of the Roman Empire, bounded on the west by the country of the Helvetii, on the east by Noricum, on the north by Vindelicia, and on the south by Cisalpine Gaul. It thus comprised the districts occupied in modern times by eastern and central Switzerland (containing the Upper Rhine and Lake Constance), southern Bavaria and the Upper Swabia, Vorarlberg, the greater part of Tirol, and part of Lombardy. The northern border of Raetia was part of the Limes Germanicus, stretching for 166 km along the Danube. Raetia was linked to Italy across the Alpine Resia Pass by the Via Claudia Augusta.