There are the remains of an Irish round tower on the edge of the Armoy village. An early monastery was founded about AD 460 by Saint Olcán, a disciple of Saint Patrick. The only trace of an early monastery is the stump of the round tower, which stands in the grounds of St Patrick's Parish Church. The tower is about 11 m high and has three storeys. At one time, Armoy was the main religious settlement in the Irish part of the kingdom of Dál Riata.
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.