The place of the Tarvastu castle has been an ancient fortified stronghold. A medieval Order castle, surrounded by a moat, was built at the River Tarvastu, during the 14th century, and exploded in 1596. In the yard of the front stronghold, there is a light-coloured classicist chapel, founded in 1825, to be burial place of the v. Mensenkampff's family. The suspension bridge, which connected the hill of the front fort with the other bank, is now in the Viljandi Castle Hills.
Reference: Vortsjarv.ee
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.