There are traces of Roman occupation including a fort, built in the late 300s AD, above the Alderneys only natural harbour. The Alderney Nunnery was probably located on the site of this one best preserved Roman forts in the British Isles.
The 26-foot tall Roman tower features 10-feet-thick walls. Built of stone and Roman concrete, many of the outer walls are still standing however only fragments remain of the tall tower that would have stood inside the walls, there is a similarity to Roman signal stations built in Yorkshire.
The British are believed to have refurbished the Roman fort in 1793, leveling off the tower walls in the process, according to Heritage Daily. When the German’s invaded the island it appears they inserted a Type 501 bunker neatly between the tower ruins, using the north and south internal walls effectively as shuttering to pour their concrete, according to Dr. Jason Monaghan, who is helping lead the excavation efforts.
The site is newly opened after a major make over. There are story boards, an information room, large WWII bunker and much, much more to explore on this amazing heritage site.
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.