Dun Ardtreck is a D-shaped dun, or 'semi-broch', situated on a rocky knoll on the edge of a cliff overlooking the sea. It encloses an area of about 13 by 10 metres. It was constructed with a ruidmentary hollow-wall. The entrance is particularly well-preserved with door-checks characteristic of brochs. The entrance to a guard cell led off to the right behind the door-checks.
Dun Ardtreck was excavated by Euan W. MacKie in 1964-1965 as part of an exercise to establish the development of the broch. It had been built in two stages: a roughly level platform was constructed and on this was set the galleried wall. Charcoal from the platform was radiocarbon dated to 115 BC. The first phase of occupation seems to have been very short and it appears to have ended in violence and destruction. The second phase was dated from the pottery finds to the middle of the 2nd century AD. The finds from this period included iron tools, bronze ornaments and glass ring-heads as well as Roman Samian ware pottery sherds and a piece of a Roman bead.
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.