Berlanga de Duero Castle, which is now in ruins, dates back to the 15th century though it was built over a 10th-century Muslim fortress of which there are no remnants. It originally belonged to the Tovar family who ordered the construction of the village’s collegiate. This castle played an important role, along with the defensive wall, in defending the villages along the Douro riverbanks during the Muslim Conquest. Of the remains that are left of the castle, it is worth noting the keep which is in very good condition.
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.