The Ipf is a mostly treeless mountain (668 metres)with a prehistoric hill fort on its top. The fort is situated on an isolated hill, with a flattened summit surrounded by a stone wall, ditch and large counterscarp (outer bank). The overall diameter is about 180 metres. There are also extensive ramparts traversing the slopes to protect a large enclosed area and entranceway. There is evidence of occupation from the Bronze Age through the Iron Age to the early Celtic La Tene period, a span of almost a thousand years (1200 BC - 300 BC).
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.