The position and the layout of Stahlberg Castle clearly indicate that it is founded in the 12th century. It is situated on a rocky projection to the northwest of the town. The ring wall, parts of which have been rebuilt, surrounds the whole area and is rectangular in shape with several openings. A prominent circular tower that rises next to the gateway like a keep was added at the start of the 13th century and secures the narrow entrance with its curtain wall and a ditch. This part of the design is based on a similar feature at Stahleck Castle. The original keep can probably be identified in the ruins of an angular tower in the upper part of the castle.
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.