Burgau Castle was originally surrounded by a water trench which gave the name to the village Burg in der Au ('Castle in the Meadow'). The fortification was of great strategic importance against ongoing Turkish and Hungarian invasions from the East across the nearby Lafnitz river. The castle was first mentioned in 1367 as a property of the lords of Puchheim. Then the municipality and the castle were given as a feoff to the house of Neitberg before being handed over to Weikhard von Polheim. Thanks to newly built fortifications commanded by Erhard von Polheim, the invading Turks could be defied in the years 1529 and 1532. In the end, the indebted property of Burgau was given to Mathias von Trauttmannsdorff, who oppressed the local population with high socage fees. In 1704, Eastern Styria was heavily devastated by attacking Kuruz, Hungarians rebelling against the Habsburgs. The mayor saved the village by offering weapons and money to the invaders.
Today the renovated Burgau Castle houses the mayor's office, apartments and a café. The festive hall and the arcaded courtyard are used for indoor and outdoor cultural events and annual exhibitions for Christmas and Easter.
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.