Singidunum (Singidunum) was an ancient city which later evolved into modern Belgrade, the capital of Serbia. The name is of Celtic origin, going back to the time when Celtic tribe Scordisci settled the area in the 3rd century BC, following the Gallic invasion of the Balkans. Later on, the Roman Republic conquered the area in 75 BC and incorporated it into the province of Moesia. It was an important fort of the Danubian Limes and Roman Legio IV Flavia Felix was garrisoned there since 86 AD. Singidunum was the birthplace of the Roman Emperor Jovian. It was sacked by Huns in 441, and by Avars and Slavs in 584. At the beginning of the 7th century, the Singidunum fort was finally destroyed.
A large part of Belgrade's downtown belongs to the "Archaeological Site of Singidunum", which was declared a protected zone on 30 June 1964.
The Scythian and Thracian-Cimmerian tribes traversed through the region in 7th and 6th century BC. The Gallic invasion of the Balkans occurred in the 4th and 3rd century BC. One of the Celtic tribes, the Scordisci, settled around the strategic hilltop at the meeting of the two rivers (modern Danube and Sava). They are credited with establishing Singidunum, which was mentioned for the first time in 279 BC, as an already fortified settlement.
There is only limited archaeological evidence from the city's foundational period as there were almost no traces left of the Celtic town, except for some burial sites with grave goods - the necropolises found at the locations in the modern neighborhoods of Karaburma and Rospi Ćuprija. These contained valuable artistic artefacts, that belong to the warriors of the Scordiscan tribe. A considerable Celtic cultural influences have been woven into the spiritual culture of the Singidunum inhabitants, and later mixed with Roman classical cultural elements.
The Celtic fortification was a primitive one, located on top of Terazije ridge, above the confluence of the Sava into the Danube, where Belgrade Fortress still stands today.