Zwing Uri is a ruined medieval castle north of Amsteg, today in the territory of the municipality of Silenen.
The castle is notable for its role in Swiss historiography as the first fortress destroyed in the Burgenbruch at the beginning of the Swiss Confederacy. The slighting of Zwing Uri (Twing Üren) is mentioned in the White Book of Sarnen, a Swiss chronicle of 1470. The event is placed in the year 1307 by the Chronicon Helveticum (1570).
The site had been occupied since the Bronze Age. By 1150, there had been a farmstead with three buildings. By the early 13th century, the dwelling was replaced by a defensive tower. During the period of 1310 to 1320, the tower was still standing, and there are traces of a planned expansion into a full castle with a ring wall and a moat. This expansion was interrupted at about six weeks into the construction work, and the castle was abandoned in ca. 1320, i.e. 13 years after the traditional date of the Burgenbruch.
The site remained unoccupied until 1868, when a restaurant was built, using stones from the ruin. The remains were secured in 1928, when the ruin was acquired by the Schweizerischer Burgenverein. Archaeological excavations of the ruin were performed in 1978.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.