The Fortress can be visited
Porta Claudia

A former fortification, the Porta Claudia is strategically located at the narrow point of the Scharnitz Pass in the Isar Valley. Near the Bavarian border at Mittenwald in Tyrol, Austria, it secured an important crossing and can still be visited today as a ruin.
History+
The construction of the barrier began in 1633 during the Thirty Years' War, commissioned by Claudia de’ Medici, Archduchess of Austria and sovereign of Tyrol. Named after her, the fortress served to secure the passage from Bavaria to Tyrol and was expanded in 1670. In 1786, Goethe described the border fortification in his travel reports. During the Third Coalition War in 1805, French troops under Marshal Michel Ney besieged the Scharnitz and Leutasch passes. The defense included not only the facilities near Scharnitz but also the Leutascher Schanz, located a few kilometers to the west.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Chianti at de.wikipedia / CC BY-SA 3.0 via Wikimedia Commons
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: 47.3961, 11.2651