Pen Dinas is the name of a large hill just south of Aberystwyth where an extensive Iron Age, Celtic hillfort of international significance is situated.
The hillfort actually consists of two separate forts built many years apart, which were later combined to form a larger structure. The first fort to be constructed was on the lower northern summit. It consists of an outer ditch and inner rampart of rubble. It would originally have been surmounted by a wooden palisade. The main gateway is on the western side and is formed by a stone lined gap in the ditch and bank.
After this first fort was eventually abandoned several decades passed before work began on a new fortification on the higher summit to the south. This second site is better protected by a steeper slope on the western side. To the south and east huge terraced earth works were built faced with shale which would again have been topped with a wooden palisade. Entrance into the southern fort is via gateways to the north and south. They are both formed of narrow passageways through the earthworks and would also have had timber bridges to cross the ditches. The northern gateway is kinked to the left, probably to aid defence by slowing down attackers.
Eventually the southern fort too became derelict and there is evidence that some of the wooden structures by the northern gateway were burnt. This could be following a hostile raid on the fort or because lack of resources lead to its abandonment. However, sometime later the defences of the southern fort were rebuilt this time to a different layout.
The final phase in the fort's construction was the refortification of the northern section and the construction of banks and ditches to connect the two forts together thereby enclosing the entire hill top. The coming of the Romans to the area in about 74 AD may have led to the forcible abandonment of the fort or it may have fallen from use before then but the only evidence from the Roman period is an early 4th-century coin hoard of Roman currency possibly left as an offering to a shrine on the hill.
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.