Porto Palermo Castle was probably built by the Venetians as it could be relieved by sea and it has the same triangular plan with round towers found in the Venetian fort at Butrint. At that time the identity of its builders ought to have been clear, from a plaque above the entrance gate. This plaque is now missing but the weathering of the stones clearly shows that it has not been missing for many decades. Almost certainly this plaque had a carving of the lion of St. Mark. The most plausible explanation of the error found in the guide books is a rewriting of history in the communist period. Re-ascribing a colonial legacy to construction by an Albanian fits a nationalist isolationist agenda.
The castle would have been vulnerable to cannon fire from the hill above and this also suggests an early date for its construction when cannon had not developed the range they had later. In 1662 the Venetians feared the Turks would recondition it. In 1803 Ali Pasha offered the castle and port to the Royal Navy. At which time the fort only had 4 or 5 cannon implying that Ali Pasha did not see the fort as important for him.
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.