Porta Claudia, Mountain fortification in Scharnitz Pass, Austria

Porta Claudia is a mountain fortification built across the Scharnitz Pass, at the historical border between Austria and Bavaria. The remaining walls run along the rock face and completely block the narrow valley entrance.

Tyrol was granted the right in 1632 to build the Porta Claudia at the Scharnitz Pass on Werdenfels territory, to guard against the advancing Swedish army in the Thirty Years' War. Claudia de' Medici, Archduchess of Austria and Princess of Tyrol, ordered the valley barrier and it was named after her. In 1670 the fortress was expanded; in 1703, during the Bavarian Rummel, it was taken by surprise and the powder magazine was blown up, with the damage soon repaired. A treaty of 28 May 1766 confirmed Tyrol's possession of Scharnitz and the fortification.

The name honours Claudia de' Medici, Archduchess of Austria and Princess of Tyrol, who ordered the barrier built to guard the crossing from Bavaria. The defences were not limited to Scharnitz: a few kilometres west, at the entrance to the Leutasch valley, stood the Leutascher Schanz, whose ruins can still be seen near the old customs post at Unterleutasch-Schanz.

The fortification is reachable on foot from the village of Scharnitz, with the path leading through the valley entrance and past the walls. Sturdy footwear is recommended, as the ground is uneven and mountain weather can change quickly.

The 1805 siege turned on a mountain track above the Lautersee and Ferchensee lakes, past the Grünkopf (1,587 m). Led by Mittenwald guides, French troops under Marshal Ney climbed it and attacked the Leutascher Schanz from behind on 4 November 1805. The path is still marked as the Franzosensteig on hiking maps.