In 1383, the Davensberg branch of the noble lords of Büren acquired a newly constructed castle from Archbishop Friedrich of Cologne as a fief. It was intended as an outpost in the Almetal and was to be jointly owned by the Davensberg and Cologne Archbishop.
In 1394, the Davensbergs pawned the castle to Johann von Scharfenberg, a branch of the Padberg family. Concurrently, the noble lords of Büren pawned their half of the castle and town of Alme to Hermann von Padberg. The redemption of the Ringelstein castle took place in 1399 by Berthold von Büren.
While often suggested to defend against the Padbergs, there is no evidence linking the pawning and redemption of Ringelstein and Alme castles for this purpose.
In 1458, the castle was granted as a fief to the Landgrave of Hesse. During the Thirty Years' War, Ringelstein became a venue for witch trials, with a judicial site and torture facilities. In 1631, 55 people were convicted and executed as witches within 30 days. After 1802, Ringelstein declined in significance and fell into ruin.
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.