Around 516, Saint Einion, king of Llyn, invited the Breton Saint Cadfan to move to the Bardsey Island from his first residence in Tywyn. Under Cadfan's guidance, St Mary's Abbey was built. In 1188, the abbey was still a local institution but, by 1212, it belonged to the Canons Regular. Many people still walk the journey to Aberdaron and Uwchmynydd each year in the footsteps of the saints, although today only ruins of the old abbey's 13th century bell tower remain. A Celtic cross amidst the ruins commemorates the 20,000 saints reputed to be buried on the island.
The Dissolution of the Lesser Monasteries Act of 1536, on the orders of Henry VIII, resulted in St Mary's Abbey being dissolved and its buildings demolished in 1537.
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.