Roman Britain is the part of the island of Great Britain controlled by the Roman Empire from CE 43 until ca.

CE 410.

The Romans refer to the imperial province as Britannia, which eventually comprises all of the island of Great Britain south of the fluid frontier with Caledonia (Scotland).

Before the Roman invasion, begun in CE 43, Iron Age Britain already had established cultural and economic links with Continental Europe, but the Roman invaders introduce new developments in agriculture, urbanization, industry and architecture.

Besides the native British record of the initial Roman invasion, Roman historians generally mention Britannia only in passing.

Thus, most knowledge of Roman Britain has derived from archaeological investigations, and the epigraphic evidence lauding the Britannic achievements of an Emperor of Rome, such as Hadrian (r. CE 117–38) and Antoninus Pius (r. CE 138–61), whose walls demarcate the northern borders of Roman Britain.

The first extensive Roman campaigns in Britain were by the armies of Julius Caesar in 55 and in 54 BC, but the first significant campaign of conquest does not begin until CE 43, in the reign of the Emperor Claudius.

Following the conquest of the native Britons, a distinctive Romano-British culture emergeS under provincial government, which, despite steadily extended territorial control northwards, Is never able to exert definite control over Caledonia.

The Romans demarcate the northern border of Britannia with Hadrian's Wall, completed around the year 128.

Fourteen years later, in CE 142, the Romans extend the Britannic frontier northwards, to the Forth-Clyde line, where they construct the Antonine Wall, but, after approximately twenty years, they then retreat to the border of Hadrian's Wall.

Around the year 197, Rome divideS Britannia into two provinces, Britannia Superior and Britannia Inferior; sometime after CE 305, Britannia Is further divided, and made into an imperial diocese.

For much of the later period of the Roman occupation, Britannia Is subject to barbarian invasions and often comes under the control of imperial usurpers and pretenders to the Roman Emperorship.Most Romans depart from Britain around the year 410, which begins the sub-Roman period (CE 5th–6th c.), but the legacy of the Roman Empire is felt for centuries in Britain.