Gonio fortress (previously called Apsaros, or Apsaruntos), is a Roman fortification in Adjara, at the mouth of the Chorokhi river. The oldest reference to the fortress is by Pliny the Elder in the Natural History (1st century AD). There is also a reference to the ancient name of the site in Appian’s Mithridatic Wars (2nd century AD). In the 2nd century AD it was a well-fortified Roman city within Colchis. The town was also known for its theatre and hippodrome. It later came under Byzantine influence. The name 'Gonio' is first attested in Michael Panaretos in the 14th century. In addition, there was a short-lived Genoese trade factory at the site.
In 1547 Gonio was taken by the Ottomans, who held it until 1878, when, via the San-Stefano Treaty, Adjara became part of the Russian empire. In the fall of 1647, according to Evliya Çelebi, Gonio was captured by a Cossack navy of 70 chaikas, but quickly recovered by Ghazi Sidi Ahmed, ruler of the Tortum sanjak, with a force of 1,000 Turks and 3,000 'Mingrelians'.
The grave of Saint Matthias, one of the twelve apostles, is believed to be inside the Gonio fortress. However, this is unverifiable as the Georgian government currently prohibits digging near the supposed gravesite. Other archaeological excavations are however taking place on the grounds of the fortress, focusing on Roman layers.
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.