Rome’s history is said to have begun in 753 BCE with the founding of the city by legendary twins Romulus and Remus, who the legend says were raised by a wolf after being abandoned as babies.

The story of Romulus and Remus is just one of many that tell of Rome’s founding, but it remains the most enduring; however, the truth surrounding the actual events of Rome’s foundation is unknown.

Regardless of its beginnings, Roman influence expanded well beyond its central Italian powerbase quickly.

At its height, in 117 CE, the Roman Empire (Latin: Imperium Romanum) encompassed approximately 5 million square kilometres, stretching from Hadrian’s Wall in the north of England to the shores of the Red Sea along the coast of Egypt. For comparison, the modern European Union encompasses approximately 4.4 million square kilometres. The period between 27 BCE and 180 CE is known as the Pax Romana (Roman Peace); it was a time of stability and peace throughout the empire.

When an empire extends too far, cracks start to appear. With such a large territory for Rome to control, problems began to arise.

The decline of Roman control was not the result of one event, but a culmination of many events over a period of time. Historians throughout the years have considered many reasons that lead to the fall of the Roman Empire. As with many civilisations, decline and collapse is not the result of one factor.

To restore stability, the Emperor Diocletian split the Empire in two in 286 CE, with each territory to be ruled by a senior and junior emperor, two in the east and two in the west. It was hoped that with smaller territories to administer, the four emperors could more easily address the issues facing the Empire.

Hostilities towards Christians continued under successive emperors. However, the outlook for the Christians changed in the rule of Emperor Constantine.

During the period known as the Civil Wars of the Tetrarchy (306-324 CE), Constantine was engaged in a struggle against the other rulers of the Empire, each refusing to acknowledge the others as legitimate emperors under the four-emperor system. Prior to a battle against rival Emperor Maxentius in 312 CE, Constantine is said to have had a dream in which the Christian God told him to mark his army with the sign of Jesus Christ’s initials. Constantine ordered the shields and standards of his army be marked with the symbols and marched to battle. He was victorious, despite being outnumbered, and believed the victory was a favour of the Christian God.

Following the battle, Emperor Constantine converted to Christianity, but he maintained a tolerance of the old traditions of Rome.

Along with co-emperor Licinius, Constantine signed the Edict of Milan, which granted rights and tolerance to Christians and all other religions in the Empire if the people remained loyal to the emperor.

Licinius later went on to resume persecuting Christians.

Eventually Constantine and Licinius would go to war. Constantine was victorious and became the sole ruler of Rome. He would move the main capital of the Empire to the city of Byzantium, which was renamed Constantinople (Latin: Constantinopolis = The City of Constantine) around 330 CE. The city would retain this name until the early twentieth century.

By the late third century CE, the Western Empire had become a shadow of its former self. Relationships with surrounding kingdoms and tribes were worsening, and the borders of the western territories were constantly under siege, especially from the peoples known as the Goths and Vandals. Conflict between religious groups was still causing problems for the government, and trade and taxation were disrupted due to these conflicts.

This map shows the state of the Roman Empire in the year 400 CE. The western Empire can be seen in yellow outline and the eastern Empire can be seen in red. The map also highlights “Barbarian nations” with blue. This map was printed in 1709 from historical sources. It includes insets of the “modern world” to put the Roman Empire in context.