The castle tower is a fragment of the oldest building in Tukums. It is believed that the construction of the castle in Tukums was commenced in 1277 by the Livonian Order. The castle was surrounded by a 7.5 m tall and 1.6 m wide stone wall. The castle defence was ensured by an artificial, deep moat and its position on the high bank or the River Slocene. Only a small stone wall fragment has been preserved from the castle, but the castle tower built in the 18th century in turns hosted premises for a prison and the caronal stocks (granary). Nowdays, it hosts the history museum of Tukums town, telling about the town's history from the ancient times up until the modern 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.