The artillery fortress was built in 1939-1941 as part of the border fortifications in the Rhine Valley. With its four built-in guns of 7.5 cm it dominated the southern part of the Lake of Constance in the north and the bridges over the Rhine up to Montlingen in the south. Heldsberg was one of the biggest border fortifications of Switzerland. Operating until 1990, the fortress became a museum in 1993.

Museum: Fortress Museum Heldsberg
City: St. Margrethen
Country: Switzerland
Address: Obere Heldsbergstrasse 5
Website: https://www.festung.ch