Borsh Castle (also known as Sopot Castle) dates from Antiquity, and its fortifications follow the trace of an acropolis, with four subsequent phases of reconstruction, ranging from the early Byzantine period to the late Middle Ages.
The site is first mentioned in the early 13th century, when archbishop Demetrios Chomatenos wrote of the 'archonship of Sopotos', part of the region of Vagenetia. In 1258, the Despot of Epirus Michael II Komnenos Doukas gave the castle along with Buthrotum and the island of Corfu as dowry for his daughter Helena to Manfred, King of Sicily. It came back under Epirote control soon thereafter, before being once again ceded by Nikephoros I Komnenos Doukas to Charles I of Anjou in 1279. The area returned again to Epirote hands in the subsequent decades, but in the Epirote rebellion against Palaiologan Byzantine rule in 1338–39, it remained loyal to Emperor Andronikos III Palaiologos.
Following the Ottoman conquest, a cadaster from 1431 lists Sopot with 60 households, and as capital of a nahiye. In 1456, troops of King Alfonso V of Aragon were operating in the area of Sobato against the Ottomans. In 1470 it was under Venetian control, under the jurisdiction of the governor of Corfu; at the end of the Ottoman–Venetian War of 1463–1479, the Ottomans laid claim to it and apparently received it, for in 1488 the local Albanian population rebelled against Ottoman rule.
The walls of the castle, which follow the ancient fortifications, survive. In the interior, the medieval fortress was divided through a wall in two. Triangular towers were added later, probably during the middle Byzantine period. In the interior of the castle stand ruins of various buildings and cisterns.
References:Prunn Castle is perched on an almost vertical Jurassic outcrop high above the Altmühl river valley south-west of Regensburg. Its impressive appearance from a distance is matched by the views from the castle of the surrounding Altmühltal countryside.
Lords of Prunn were first mentioned in 1037, and they will have certainly chosen the site because of its favourable position on several transportation routes. The castle itself dates from around 1200, a time when many castles were being built. The Danube region centring around Kelheim became very important in this period under the Bavarian duke Ludwig I. One of the oldest parts of the castle is the 31-metre keep.
In 1288, Duke Ludwig of Bavaria acquired the castle from the lords of Prunn-Laaber. In the first half of the 14th century the duke then invested the Fraunberg vom Haag family with the castle.