Early Anglo-Saxon settlement in the London area was not on the site of the abandoned Roman city, although the Roman city walls remained intact.
Instead, by the 7th century a village and trading centre named Lundenwic, was established approximately one mile (1.6km) to the west of Londinium (named Lundenburh or "London Fort" by the Saxons), probably using the mouth of the River Fleet (near present day Fleet Street) as a trading ship and fishing boat harbour.

Lundenwic

Lundenwic in the early eighth century was described by the Venerable Bede as "a trading centre for many nations who visit it by land and sea". The word "wic" was an Old English word for 'trading town', so Lundenwic literally meant 'London trading town'. Archaeologists were for many years puzzled as to where early Anglo-Saxon London was located, as they could find little evidence of occupation within the Roman city walls from this period. However in the 1980s it was 'rediscovered' after extensive excavations. Recent excavations in the Covent Garden area have uncovered the considerable Anglo-Saxon settlement dating back into the 7th century. They also show that the settlement covered about 600,000 square metres, stretching from the present-day National Gallery site in the west, to Aldwych in the east.

By about 600 AD Anglo-Saxon England had become divided into a number of small kingdoms. From the middle of the 6th century, London was incorporated into the East Saxons' kingdom, which extended as far west as St Albans and included all of later Middlesex, and probably Surrey too for a time.

In 604 Saeberht of the East Saxons converted to Christianity and London received Mellitus, its first post-Roman bishop. At this time Essex owed allegiance to the Bretwalda Ethelbert of Kent, and it was under Ethelbert that Mellitus founded the first St. Paul's Cathedral, traditionally said to be on the site of an old Roman Temple of Diana (although Christopher Wren found no evidence of this). This would have only been a modest church at first and may well have been destroyed after he was expelled from the city by Saeberht's pagan successors in 616. Christianity did not return until around 675 when Theodore of Tarsus installed St Eorconweald as bishop.

The new town came under direct Mercian control in 670 as the East Saxon kingdom of which it had once been part was gradually reduced in size and status. After the death of the Mercian king Offa in 796, control of London was disputed between Mercia and Wessex.

Alfred the Great

Attacks from Vikings became increasingly common from around 830 onwards. London was attacked in 842 in a raid that was described by a chronicler as the "great slaughter". In 851 another raid on London, reputedly involving 350 ships, came to plunder the city. In 865 the Viking "Great Heathen Army" launched a large scale invasion of East Anglia and soon overran East Anglia, Mercia and Northumbria and came close to controlling most of England. By 871 they had reached London, and are believed to have camped within the old Roman walls during the winter of that year. Although it is unclear what happened during this time, London may have come under Viking control for a period. In 878 however, West Saxon forces led by King Alfred the Great defeated the Vikings at the Battle of Ethandun and forced the Viking leader Guthrum to sue for peace. The Treaty of Wedmore and the later Treaty of Alfred and Guthrum divided England into Alfred's Saxon controlled kingdom and Danish controlled Danelaw.

English rule in London was restored by 886. King Alfred quickly set about establishing fortified towns or "Burhs" across England to improve defences, London was no exception. Within ten years, settlement within the old Roman walls was re-established, but known as Lundenburh. The Roman walls were repaired and the defensive ditch re-cut. This move was effectively the beginning of the present City of London, the boundaries of which are still to some extent defined by the ancient city walls.
As the focus of the city was moved back to within the old Roman walls, the older settlement of Lundenwic was largely abandoned and gained the name of Ealdwic or "old settlement". The name survives today as Aldwych.

The Norman invasion of Britain in 1066 is usually considered to be the beginning of the Medieval period. William, Duke of Normandy, killed English king Harold Godwinson in the Battle of Hastings. Having conquered Hampshire and Kent, William and his army turned to London. Having failed to cross London bridge at Southwark, William's army marched clockwise around London and waited to the north-west at Berkhamsted. Where, having realised that resistance was pointless, a delegation from London arrived to surrender the city, and recognise William as King. William soon granted a charter for London in 1067 which upheld previous Saxon rights, privileges and laws. It is often wrongly presumed that Normans were French in origin. Their name is a contraction of North Men and Norse Men, and they were in fact Viking settlers from Scandinavia, with Normandy being a separate fiefdom, through treaty with the French crown.