The Fortress can be visited
Ouvrage Hochwald

The Ouvrage Hochwald is an artillery work of the French Maginot Line in Alsace. It is the largest fortress of its kind in the region, distinguished by its special construction, which originally envisaged a rear battery with long-range gun turrets.
History+
The Ouvrage Hochwald played an active role during the Phoney War from 1939 to 1940. In October 1939, it supported French patrols, and in November of the same year, it shelled German minelayers. During the Western Campaign in 1940, the facility came under fire from June 16, when it engaged German troops advancing on Lembach. This was followed by artillery shelling and Stuka attacks, which were repeated on June 20 and 22. Despite the dropping of 140 aerial bombs, some weighing up to 1000 kilograms, the work remained largely undamaged.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Lignemaginot.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 48.9969, 7.8734