Schloss Ringenberg is a moated castle located in the city of Hamminkeln, North Rhine-Westphalia. It stands in the southeast of the Ringenberg district, which gave the castle its name.
The castle traces its origins to a 13th-century fortress, built in the strategically important border region between the County of Cleves, the Archbishopric of Cologne, and the Prince-Bishopric of Münster. After being destroyed by Dutch troops, the estate came into the possession of Baron Alexander von Spaen in the 17th century, who rebuilt it.
Designated a historic monument in 1984, the site was listed as an archaeological monument three years later. Today, the castle is owned by the city of Hamminkeln, which operates its civil registry office there. The building also houses an artist studio center run by the Derik Baegert Society and a restaurant.
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.