Ducové is famous for an archaeological site on the Kostolec hill, where an important Great Moravian castle has been unearthed. The castle, including a small palace, a Christian rotunda church, and a graveyard of local nobles, served as the administrative center of the Váh river valley during the 9th century and the first half of the 10th century. It was founded after the nearby Nitrian castle in Pobedim was destroyed during unification of Great Moravia by Mojmír I.
Ducové castle was destroyed itself by Magyar invaders around 955. Some parts of the castle (such as its palisades) have been reconstructed by archaeologists. Excavations of older settlements from the Stone Age, Bronze Age and the Roman era indicate that Ducové benefited from its location on the Amber Road well before the Great Moravian era.
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.