In the 12th century Muri Abbey owned a farm on the Horben hill. Then, in 1700 Abbot Placidus Zurlauben build a rest home for the sacristan on the hill. The lower Prince-Abbot Gerold Haimb had the Chapel of St. Wendelin and Ubaldus built in 1730 near the home. Between 1752-76, during Abbot Bonaventure Bucher's term of office, the house and chapel were rebuilt into their present form. In 1762 the interior was furnished with wall paintings and rococo statues by Caspar Wolf.
After the dissolution of the monasteries in the Aargau in 1841, Horgen Castle was acquired by the Canton. In 1842 it was sold to a private purchaser. Initially it belonged, together with the nearby monastery, to the National Councilman Peter Suter from Sins. From 1885-1913 it was owned by District Officer Kaspar Weber of Muri, and since 1913 by the family Borsing. In 1979-80 the castle underwent a total restoration.
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.