Belgrade Fortress

The Belgrade Fortress (Serbian: Београдска тврђава, Beogradska tvrđava, Hungarian: Nándorfehérvár), consists of the old citadel (Upper and Lower Town) and Kalemegdan Park (Large and Little Kalemegdan) on the confluence of the Sava and Danube rivers, in an urban area of modern Belgrade, Serbia. Located in Belgrade's municipality of Stari Grad, the fortress constitutes the specific historical core of the city. As one of the most important representatives of Belgrade's cultural heritage, it was originally protected right after World War II, among the first officially declared cultural monuments in Serbia. The fortress was declared a Monument of Culture of Exceptional Importance in 1979, and is protected by the Republic of Serbia. It is the most visited tourist attraction in Belgrade, with Skadarlija being the second. Since the admission is free, it is estimated that the total number of visitors (foreign, domestic, citizens of Belgrade) is over 2 million yearly.

Belgrade Fortress is located on top of the 125.5 metres (412 ft) high ending ridge of the Šumadija geological bar. The sandbank stretches at least from the city's Tašmajdan section, originating from the Miocene period, and the oldest stages of the ancient Pannonian Sea. The cliff-like ridge overlooks the Great War Island (Serbian: Veliko ratno ostrvo) and the confluence of the Sava river into the Danube, and makes one of the most beautiful natural lookouts in Belgrade. It borders the neighborhoods of Dorćol (north and north-east), Stari Grad (east) and Kosančićev Venac (Savamala; south). It is bounded by 3 streets: Boulevard of Vojvoda Bojović, Tadeuša Košćuška, Pariska, plus the railway along the riverside.

Belgrade Fortress is the core and the oldest section of the urban area of Belgrade. For centuries, the city population was concentrated only within the walls of the fortress, and thus the history of the fortress, until most recent times, reflects the history of Belgrade itself (see: Timeline of Belgrade history). 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. The city-fortress was later conquered by the Romans, was known as Singidunum and became a part of "the military frontier", where the Roman Empire bordered "barbarian Central Europe". 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. In the period between 378 AD and 441 the Roman camp was repeatedly destroyed in the invasions by the Goths and the Huns. Legend says that Attila's grave lies at the confluence of the Sava and the Danube (under the fortress).^{[citation needed]} In 476 Belgrade again became the border between the empires: the Western Roman Empire and Eastern Roman Empire (Byzantine Empire), and the Slav-Avar State in the north.

The Celtic fortification was a primitive one, located on top of Terazije ridge, above the confluence of the Sava into the Danube, where the fortress still stands today. Celts also lived in small, open and fortified settlements around the fort, called oppida. Since it is not known for sure where the Celtic fort was; some historians suggest that it was rather close to the necropolises in Karaburma and Rospi Ćuprija. Celtic settlements belonged to the La Tène culture.

The original military camp was probably occupied by the soldiers from the Legio VIII Augusta from 46 AD to 69. Early Singidunum reached its height with the arrival of Legio IV Flavia Felix which was transferred to the city in 86 AD and remained there until the mid 5th century. The presence of Legio IV prompted the construction of a square-shaped castrum (fort), which occupied Upper Town of today's fortress. Construction began at the turn of the 2nd century AD as since the early 100s, Legio IV Flavia Felix became permanently stationed in Singidunum. At first, the fortress was set up as earthen bulwarks and wooden palisades, but soon after, it was fortified with stone as the first stone fort in Belgrade's history. The remains can be seen today near the northeastern corner of the acropolis. The legion also constructed a pontoon bridge over the Sava, connecting Singidunum with Taurunum.

Rectangular castrum covered what is today the Upper Town and the Kalemegdan Park. The castrum had tall walls, built from the white Tašmajdan limestone and spread over the area of 16 ha (40 acres) to 20 ha (49 acres), being shaped as an irregular rectangle (approximately 570 by 330 m (1,870 by 1,080 ft)).

The Byzantine Emperor Justinian I rebuilt the fortress around 535. In the following centuries the fortress suffered continuous destruction under the Avar sieges. The Slavs (Serbs) and Avars had their "state union" north of Belgrade with the Serbs and other Slavic tribes finally settling in the Belgrade area as well as the regions west and south of Belgrade in the beginning of the 7th century. The name Belgrade (or Beograd in Serbian), which, not just in Serbian but in most Slavic languages, means a "white town" or a "white fortress", was first mentioned in AD 878 by Bulgarians. The fortress kept changing its masters: Bulgaria during three centuries, and then the Byzantines and then again Bulgarians. The fortress remained a Byzantine stronghold until the 12th century when it fell in the hands of the newly emerging Serbian state. It became a border city of the Serbian Kingdom, later Empire with Hungary. The Hungarian king Béla I gave the fortress to Serbia in the 11th century as a wedding gift (his son married the Serbian princess Jelena), but it remained effectively part of Hungary, except for the period 1282–1319.

After the Serbian state collapsed following the Battle of Kosovo, Belgrade was chosen as the capital of Despot Stefan Lazarević in 1402. Major work was done to the ramparts which were encircling a big thriving town. The lower town at the banks of the Danube was the main urban center with a new built Orthodox cathedral. The upper town with its castle was defending the city from inland. Becoming a major trade and cultural center, Belgrade became a significant immigration town, with immigrants settling from other parts of Serbia, Dubrovnik, Bulgaria, Hungary, Germany, Italy and Venetia. Population blossomed, so the lower city of the fortress, which was the busiest part of the city, had to be significantly expanded.