King Doniert's Stone consists of two pieces of a decorated 9th-century cross near St Cleer. The inscription is believed to commemorate Dungarth, King of Cornwall, who died around 875.
The site consists of the remains of two granite cross-shaft fragments dating from the 9th–11th century, and an underground passage and cross-shaped chamber below the crosses, thought to be either the remains of tin workings or a possible oratory. The northern cross, the Doniert Stone, is 1.37 metres high with panels of interlace decoration on three sides and inscription doniert rogavit pro anima carved in half uncial or insular script. The inscription translates as 'Doniert has asked [for this to be made] for his soul['s sake]'.
The inscription is thought to refer to the local ruler Dumgarth (or Dwingarth), who is recorded in the early Welsh chronicle known as the Annales Cambriae as having drowned in around 875 AD. It has a mortise slot and a plinth at the base. It is notable for being the only inscription to a Cornish King also known from documentary sources.
The southern cross, sometimes referred to as the Other Half Stone, is 2.1 metres (6 ft 11 in) high with a panel of interlace decoration on the east face, a broken mortise slot at the top and a plinth at the bottom.
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.