From the 6th to the 4th century BC Thracian and Scythian tribes immigrated to the region around modern Belgrade, who built the first fortification in the 3rd century BC.

Later Celtic came and illyro-thrako-Celtic tribes too, the Skordiscians, who were mentioned by the Greek-Roman authors around 279 BC. The Romans latinized the name Singidun to Singidunum, which probably means round fortress or round town.

Singidunum - posts in the defensive fortification on the Danube Limes

In the time of the Roman Empire, Singidunum was part of the defensive fortifications on the Danube limes. The strategic location of the city and the Castrum on the Via Militaris, now called Donausüdstraße, which led to the eastern section of Sirmium and to Viminatium to the south, then to Trimontium to Via Egnatia and to Constantinople, the history of Singidunum is well known until the beginning of the 7th century. The military town of Singidunum (Vicus) was supplemented with the settlement of veterans of legions in the lower city by a significant civilian city.

Singidunum becomes Garnissionsstadt am Donaulimes

In the year 86 AD, Domitian relocated the Legio IIII Flavia Felix to Singidunum in parallel with the strengthening of the imperial borders against the Dacians. The upraise of Singidunum falls into this time. The castrum was located in the upper part of today's fortress Kalemegdan. The Legion built a bridge across the Sava to the opposite settlement at Taurunum. The 6,000-man legion was one of the main military assets against the Dacian tribes on the northern side of the Danube. Due to the settlement of veterans an urban place around the legion camp grew. Today's streets in the old part of Belgrade between the streets Uzun Mirkova, Dušanova, and Kralja Petra I show the right-angled streetscape of the Roman city. The forum was located at today's Studentski Trg.

Relocation of Legio IIII Flavia Felix to Singidunum 

At the beginning of the 2nd century Trajan defeated (105-106) Dacia with the participation of the Legio IIII Flavia Felix, who participated in the campaigns since 88 and also took over parts of the road north of the Danube. With the formation of Dacia Province, Singidunum began a period of peace. In the middle of the 2nd century, Emperor Hadrian transferred Legio IV Flavia Felix back to Singidunum, giving the city the status of a municipium with greater administrative freedom, later becoming a colonia.

Road construction north of the Danube by Legio IIII Flavia Felix

After the 2nd century AD, the power of the Roman Empire begins to crumble at its borders. With the invasion of the Goths between 256 and 270, the province of Dacia is abandoned and Singidunum remains an important border post against the barbarians. Aurelian relocated all the legions back to the south bank of the Danube and reorganized the region by forming the province of Dacia ripensis.

Please read as well:

Singidunum - development in the Byzantine Empire
Belgrade - The strategic importance of the fortress

Belgrade in Serbia

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• Thracian, Celtic and Romans in Belgrade Thracian, Celtic and Romans in Belgrade
• Thracian, Celtic and Romans in Belgrade Thracian, Celtic and Romans in Belgrade
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• Thracian, Celtic and Romans in Belgrade Thracian, Celtic and Romans in Belgrade
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