Porte-du-Scex, Medieval fortress between rock face and Rhône River in Vouvry, Switzerland.

Porte-du-Scex is a 17th-century fortress squeezed between the Rhone River and a sheer limestone cliff on Route 21 in Valais, serving as a gateway between mountain valleys. The structure today functions as an exhibition space run by the municipality and sits directly beside the main highway, making it easy to spot and enter.

The Valais Diet decided in 1672 to build the castle as the residence of the châtelain of Vionnaz-Bouveret, with materials financed by the communities of the Monthey government; work began that year and the shell was finished by 1675. A toll and earlier fortifications are attested at the passage from the 13th century, and a 1591 request by the Diet led to a gate and ditch paid for by the communes of the Monthey dizain. Excavations in 1974 found walls predating the castle.

The name comes from the Latin word saxum, meaning stone, reflecting the limestone cliff that dominates the site. This connection between the building and its rocky setting shaped how locals have understood and spoken about the location.

The site is easily reached directly from Route 21 and requires no detours or special arrangements to access. The compact setting between river and cliff means visitors walk through the space fairly quickly, so plan accordingly if you want to spend time with any exhibits.

The name Scex derives from Latin saxum, a limestone crag partly cut back to let the road through. In 1358 the Tavelli lords of La Tour were granted the right by Count Amadeus VI of Savoy to set up gallows at Porte-du-Saix; later the gibbet was moved to an island in the Rhone at Proz.