Golubac
It was built in the first or second decade of the fourteenth century as a border fortress of Serbia and Hungary. The fortress was expanded during the next 150 years in four major phases. Golubac was constructed like fan, and consists of three parts: front, rear and upper city (the citadel). There is a total of 10 (9 +1) towers, and two large cart gates. The towers were later strengthened by the Turks with openings for guns, and by adding one more tower around 1480.
History of this city is full of turns. It was located within the state of Prince Lazar, who gave the surrounding villages to the metochs of monasteries. Bayezi I entered immediately after the Battle of Kosovo in 1389. It was in the hands of the Hungarians, surrendered in 1403 by Despot Stefan, when he became a vassal of Hungary. The city should, according to the contract from 1426, have been handed over to the Hungarians after the death of Despot (Stefan died in 1427), as well as Belgrade.
In front of the city is the front wall that makes the outer wall of the trench, which was probably full of water due to its connection with Danube. The city is associated with the rock Babakaj (which still protrudes from the water in the middle of the Danube) by heavy chain, so it completely controlled both the road and the river traffic through Djerdap gorge. In front of the fortress was the civil settlement, from which today only a partial explored objects remain.