Britannia Superior (Latin for "Upper Britain") was one of the provinces of Roman Britain created around AD 197 by Emperor Septimius Severus immediately after winning a civil war against Clodius Albinus, a war fought to determine who would be the next emperor. Albinus was the governor of Britannia during that civil war. Severus divided the pre-existing province of Britannia into two parts, the other being Britannia Inferior to the north with its capital at Eboracum, or modern York. Britannia Superior was the southern province of the two, with its capital at Londinium, or what is today London. Epigraphic evidence has shed some light on the extent of Upper Britain and it encompassed all of what is now Southern England as well as Wales and East Anglia. However, the official boundary between Britannia Superior and Inferior is still unclear. Most information that is gathered for this region during this time period from about the 2nd to the 3rd century is from inscriptions left upon pots, walls, and letters written by the citizens and soldiers.
Approximately a century later, around the year 293, the province was divided into Britannia Prima (with a capital at Cirencester) in the west and Maxima Caesariensis (with a capital at Londinium) in the east. This was done by Emperor Diocletian to make administrative responsibilities over the region more efficient.
During the civil war between Severus and Albinus, Albinus ordered the construction of a defending wall around Londinium. These walls were approximately 20 feet (6.1 m) high. Though the whole of the time that Britannia Superior existed Londinium was its centre for commerce and government, with the governor residing within the city.