Helme church parish was first mentioned in 1329 during a Lithuanian raid. Most of the neighbouring land was fiefed in the 15th–16th centuries. Livonian Order castle in Helme (Ordensburg Helmet) was probably built in the first half of the 14th century.
The site on a steep hill is belived to have been used as a stronghold earlier by Sackalians in the Ancient Estonia. By its ground plan the order castle was 120×60 m oval shaped structure, surrounded by two moats. There was a borough beside the castle in the Middle ages, it was mentioned until the 17th century. The castle was destroyed by the Swedes during the Russo-Swedish War in 1658. Nowadays only parts of the walls with high window holes have survived.
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.