Belgrade Fortress

The Belgrade Fortress is a cultural monument in Belgrade, Serbia in the municipality of Stari Grad [1]. It consists of the old citadel and Kalemegdan Park on the confluence of the Sava and Danube rivers [1]. The first mention of the city is when it was founded in the 3rd century BC as "Singidunum" by the Celtic tribe of Scordisci, who had defeated Thracian and Dacian tribes that previously lived in and around the fort [1]. The city-fortress was later conquered by the Romans and became a part of "the military frontier" [1]. Singidunum was defended by the Roman legion IV Flaviae, which built a fortified camp on a hill at the confluence of the Danube and the Sava rivers [1]. In the period between 378 AD and 441 the Roman camp was repeatedly destroyed in the invasions by the Goths and the Huns [1]. The Byzantine Emperor Justinian I rebuilt the fortress around 535 [1].