Saint Panteleimon Monastery was built in 1843 and became monastery in 1987. According to inhabitants of Thassos, someone wanted to build it in favor of Saint Panteleimon. The workers started the building at a location, but the next day when they wanted to continue with the construction, the part they had built was found destroyed and their tools were missing. The same happened on the following days. One day they saw footprints on the ground and followed them until they found their tools nearby a natural spring. Finally, they built the monastery at that spot.
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.