The dogal Republic of Venice purchased the area of Butrint including Corfu from the Angevins in 1386; however, the Venetian merchants were principally interested in Corfu and Buthrotum once again declined. The Venetians began to invest in Butrint in the late 15th century, which seems a likely date for the Triangular Fortress construction. Musket ports opened at both ground level and along the parapet walk. Vaulted storerooms inside the fort carried artillery platforms above to train cannon on the approach to Butrint up the Vivari Channel. In 1798, however, the fortress was slighted by General Chabot, the commander of the garrison of the French dependency of Corfu.
Triangular Fortress takes the form of an irregular triangle with a tower at each point. Originally, it stood on an island in a pre-canalised river mouth, protected by an outer siege work or ravelin (a crescent-shaped defensive wall).The keystone of one the interior buildings bears a relief of the Lion of St. Mark, the symbol of the Republic of Venice.
References:Trenčín Castle is relatively large renovated castle, towering on a steep limestone cliff directly above the city of Trenčín. It is a dominant feature not only of Trenčín, but also of the entire Považie region. The castle is a national monument.
History of the castle cliff dates back to the Roman Empire, what is proved by the inscription on the castle cliff proclaiming the victory of Roman legion against Germans in the year 179.
Today’s castle was probably built on the hill-fort. The first proven building on the hill was the Great Moravian rotunda from the 9th century and later there was a stone residential tower, which served to protect the Kingdom of Hungary and the western border. In the late 13th century the castle became a property of Palatine Matúš Csák, who became Mr. of Váh and Tatras.
Matúš Csák of Trenčín built a tower, still known as Matthew’s, which is a dominant determinant of the whole building.