The fortified town of Rello still maintains the original defensive walls and castle that were used as protection against civilisations that came from the south following the Douro River. It is the best-preserved walled enclosure in the province.
You can go inside through either one of the two gates located on the sides of the castle. The castle is protected by a fortified enclosure with circular and quadrangular towers that have elbow openings. The upper part of the towers are crowned with 15th-century machicolations and you can still see some remains of the keep, a water pool and a wall of the gate that separated the castle from the rest of the town.
In the outer enclosure, there are still gunboats in the lower section that were used for artillery.
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.