The Order of the Brothers of the Sword began building Sigulda castle in 1207. Initially, it was a castellum-type fort; following the defeat of the Brothers of the Sword in 1236, the Livonian Order modified it. During the Great Northern War, the castle was destroyed and never restored again. The south-west section of the convent building with Gothic window lintels and the main gate tower have survived to the present day.
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.