The Krögelstein castle ruins are located in the Krögelstein district of the town of Hollfeld. The noble free from Krögelstein, which were perhaps related to the also noble whale pots, are documented for the period from 1149 to 1239. It can be assumed that the Spornburg already existed at this time, but it was only mentioned in a document in 1328 as castrum. After the family died out in the middle of the 13th century, the castle came to the Bamberg bishopric. Bishop Wulfing von Stubenberg (1304–1319) pledged it in 1313 to the Bamberg cathedral chapter. Since 1400, the castle was predominantly owned by Bamberg officialsmanaged. It has been proven that it was in the hands of the von Aufseß family, then the von Giech family until it was destroyed in 1523.
On October 17, 1500, the Bamberg Prince-Bishop Heinrich III Groß von Trockau (1487–1501) returned the castle from the cathedral chapter. He gave it to Dietz von Giech as a man loan from the Bamberg monastery. Georg Wolf von Giech was married to Ottilie von Absberg, the sister of the notorious robber baron Hans Thomas von Absberg. Since he often gave shelter to his brother-in-law at the castle, the castle was destroyed in 1523 by the Swabian Federation. There was no reconstruction.
All that remains of the former castle is a buttress arch with three window slots on a dolomite rock west of the parish church.
The parish church is the former castle chapel, built around 1250, which has been used as a parish church since 1421. It has today's shape from Georg Dietrich von Giech zu Wiesentfels, Niederlind and Krögelstein. He died on July 26th, 1607. A bronze epitaph commemorates him. The keystone in the choir vault, dating back to 1607, also bears the Giech coat of arms.
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.