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 Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.