Iberg Castle is located south-west of the town of Wattwil. The central keep is six stories tall and has an entrance on the north-west corner. The keep is surrounded by a curtain wall. The castle hill is protected by moats and some walls.
Iberg Castle was built in 1240 by Heinrich von Iberg who was a vassal of the Prince-Abbot of St. Gallen. The castle was briefly conquered in 1249 following the Toggenburg fratricide and again in 1290 during the rule of the anti-Abbot Konrad von Gundelfingen in St. Gallen. It was damaged during the Appenzell Wars in 1405 and soon thereafter rebuilt. During the conflicts leading to the Battles of Villmergen (from 1699-1712), the castle was besieged in 1710. After the Treaty of Baden in 1718 it was given back to the Abbot.
During the suppression of the monasteries in 1805, the castle became privately owned. Some of the housing was demolished in 1835, but the roof and battlements were rebuilt in 1902 and 1965 by the municipality.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.