The Belgrade fortress is the oldest preserved structure in the city center. It is located in the hilly terrain above the confluence of the Danube and the Sava river. The first fortress was built by the Romans in the 1st century AD. It was one of the several bordering fortress along the Danube river with the aim to defend Roman Empire from barbarian invaders. During its long history, it was dominated by various countries: Byzantine Empire, Hungaria, Serbian Despotate, Ottoman Empire, Austria-Hungaria, Serbia … and all the time it has a military purpose. The fortress experienced numerous destructions and reconstructions. The last great reconstruction dates back in the 18th century and it was done by the Austrians. Around the fortress existed a civil settlement which over the time expanded its territory and turned into a great city of Belgrade. When the fortress lost its defending role (after the Second World War) it was transformed into the promenade and with the Kalemegdan park it represents the most visited city attraction and one of the favorite place of Belgraders.
The fortress consists of the Lower and the Upper town. Within the walls there are many gates and towers, two churches, Military museum, ZOO, the Gallery of Natural History museum, numerous sculptures and busts.
From the fortress walls there is an amazing view over the Sava and the Danube river, New Belgrade and Zemun.