Cirta (Phoenician: Tzirta) was the capital city of the Ancient Libyan Kingdom of Numidia in northern Africa (modern Algeria). Its strategically important port city was Russicada. Although Numidia was a key ally of the ancient Roman Republic during the Punic Wars (264 BC–146 BC), Cirta was subject to Roman invasions during the 1st and 2nd centuries BC, eventually falling under Roman dominion during the rule of Julius Caesar. The city was destroyed in the beginning of the 4th century and was rebuilt by the Roman Emperor Constantine the Great, who gave his name to the newly constructed city, Constantine.
Roman influence before 46 BC 
Cirta's populace was as diverse as the Roman Republic itself — alongside native Numidians were Carthaginians displaced by the Second and Third Punic Wars, as well as Greeks, Romans, and Italians. It served as an economic hub for Rome’s African empire, as it was inhabited by Roman and Italian merchants, bankers, and businessmen. Even prior to Cirta’s fall to Julius Caesar, these economic elites constituted an important segment of the city's population, as they kept it within Rome’s sphere of influence without having to be directly controlled.
Not only was Cirta an important economic site, it was also a key political and military spot within the African kingdoms. During the Second Punic War, the Battle of Cirta (203 BC) marked a decisive Roman victory for Scipio Africanus against Rome's most formidable rival in the Mediterranean — Carthage. Moreover, Rome illustrated its willingness to defend its interests in Cirta into the late 2nd century BC following the death of Micipsa, King of Numidia, in 118 BC. A power struggle ensued between his adopted son Jugurtha and his natural son Adherbal. Adherbal appealed to Rome to help broker a truce and to help evenly split the kingdom between the two heirs. Despite a senatorial commission’s seemingly successful mediation, Jugurtha besieged Cirta, killing Adherbal and Italian elites who defended him. Subsequently, Rome declared war on the kingdom to assert its hegemony in the region and to defend those citizens who lived outside of the homeland. Jugurtha’s defeat at Cirta at the hands of the Roman army is commonly referred to as the Jugurthine War.
46 BC and after 
Caesar's conquest of Northern Africa officially brought Cirta under direct Roman rule in 46 BC. It was during the rule of Augustus, however, when Cirta's territory expanded and assimilated into the empire. Augustus split Cirta into communities, or pagis, dividing Numidians and newly settled Romans. In 26 BC, the emperor attempted to increase Roman settlement in the city by supplementing the Sittiani — followers of Sittius, a man whom Julius Caesar had personally appointed to "Romanize" the city. This helped facilitate Cirta's assumption into the Roman realm, culturally and economically. These settlers, of course, were augmenting those Romans who had inhabited the city since the earlier periods of the Punic Wars, namely the Italian business elite.
In the first two centuries AD Christianity began to take root in Cirta. While little remains of African Christianity before 200, records of martyred Christians at Cirta existed by mid-century. Civil war in 311 marked the destruction of the city, however, the first Christian emperor Constantine rebuilt it in his own name in 313, calling it Constantine.
See also 
- The Cambridge Ancient History. 2nd ed., vol. 9, p. 28 London: Cambridge University Press, 1970.
- The Cambridge Ancient History. 2nd ed., vol. 9, p. 638
- The Cambridge Ancient History. 2nd ed., vol. 9, p. 29
- Roman History, Cassius Dio, vol. 43, ch. 9
- The Cambridge Ancient History. 2nd ed., vol. 10, p. 607
- Classical Gazetteer, page 321
- The Cambridge Ancient History. 2nd ed., vol. 12, p. 585, 645