Zen-Ruffinen Castle, Building in Leuk, in the canton of Valais, Switzerland

Zen-Ruffinen Castle is an architectural structure in Leuk, Swiss canton of Valais, protected as a property of national cultural significance. The complex contains several buildings constructed over centuries, with the main section and stair tower built around 1611 to 1612 and later enlarged with additional rooms and features.

The castle was built in the 17th century for the Zen-Ruffinen family, with the main section and stair tower constructed around 1611 to 1612. In the 19th century it was extended for Baron Ferdinand de Werra with new rooms added, and portions of the original wall from 1630 remain visible in the southwest corner today.

The castle takes its name from the Zen-Ruffinen family, a patrician lineage that produced two Bishops of Sion. The complex is also called Loretan or de Werra, after Baron Ferdinand de Werra, who extended it in the 19th century. The 1611–12 stair tower remains a visible marker of the family's status.

The complex stands within Leuk municipality in the Valais, at about 46.32° N, 7.64° E, on the slope above the Rhône valley. It is a Swiss heritage site of national significance, so the buildings are seen from the outside; the 1630 wall section at the south-west corner of the de Werra extension is the detail to look for. Access is on foot through the village lanes.

A section of the original 1630 wall remains visible in the southwest corner where Baron de Werra's extension begins. This standing wall serves as a direct physical marker of where the building was expanded, allowing visitors to see exactly how the structure grew over two centuries.