Burgus Erlach

The Burgus Erlach stands on a gentle slope above Lake Constance in Hörbranz, a small market town in Vorarlberg. Built in the late Roman period, it was one of a chain of watchtowers designed to guard the southern bank of the Rhine. The tower is the only surviving example of its kind in Austria, discovered in 1932 and later precisely located using ground-penetrating radar in 2011. It formed part of the late Roman Danube-Iller-Rhine Limes, a frontier system stretching from Basel to the Bodensee. The site overlooks the Rheintal, the lake, and the valley of the Leiblach, offering clear views toward Bregenz and Arbon. Its position made it the westernmost tower in the province of Raetia, linking the river and lake defences. The tower’s purpose was to relay signals between larger forts and alert nearby garrisons to threats. During the reign of Emperor Valentinian I, the frontier was strengthened with stone-built watchtowers spaced about five kilometres apart. These towers relied on line-of-sight communication, using light or horn signals to warn of attacks. The garrison likely consisted of beneficiarii, military police drawn from the ranks of the legions. Although no written records survive from Hörbranz itself, similar towers in other provinces were manned by soldiers known as burgarii, often veterans serving under the provincial governor. Visitors to the site find a quiet hillside with no visible remains above ground, but the strategic view remains unchanged. The surrounding landscape includes the wooded foothills of the Pfänder range to the east and the rolling hills toward Hohenweiler in the north. The nearby Landstraße L1 follows the route of the ancient military road, while the modern border with Germany lies just a few kilometres away. The tower’s position on parcel Erlach at Betzentobel offers sweeping views over the lake and valley, a reminder of its role in a long-vanished frontier system.