Constantine is regarded as the capital of eastern Algeria and the commercial centre of its region and has a population of about 450,000 (938,475[6] with the agglomeration), making it the third largest city in the country after Algiers and Oran.

The city later served as the base for Roman generals Quintus Caecilius Metellus Numidicus and Gaius Marius in their war against Jugurtha.

Later, with the removal of King Juba I and the remaining supporters of Pompey in Africa (c. 46), Julius Caesar gave special rights to the citizens of Cirta, now known as Colonia Sittlanorum.

In 311 AD, during the civil war between emperor Maxentius and usurper Domitius Alexander (a former governor of Africa), the city was destroyed.

Rebuilt in 313 AD, it was subsequently named in Latin as "Colonia Constantiniana" or "Constantina",[8] after emperor Constantine the Great, who had defeated Maxentius.

After taking it from the Hafsids in 1529 it was intermittently part of Ottoman Empire, ruled by a Turkish bey (governor) subordinate to the dey of Algiers.

During the Ottoman reign of Constantine, merchants traded a variety of goods such as; agricultural products, animals, embroidered textiles, leather, precious metals, swords, and pistols.

[12] During World War II, during the campaign in North Africa (1942–43), Allied forces used Constantine and the nearby cities of Sétif and Bone as operational bases.

It is also a centre of the grain trade and has flour mills, a tractor factory, and industries producing textiles, wool, linen and leather goods.

Today the most important bridges are: Constantine has in general four universities: two of them are downtown Constantine Mentouri Public University, designed by the Brazilian architect Oscar Niemeyer, and Algerian architect Rashid Hassaine, including Zerzara technical engineering pole, Zouaghi Slimane Geography and Earth Sciences Pole, and in the City of El-Khroub is the Institute of Veterinary Sciences.