After the Roman era, the London area saw a period of decline, but it wasn't the end of the City. Anglo-Saxon settlers eventually established a town just west of the old Roman ruins – a trading hub they called Lundenwic (near today's Covent Garden).
By the 7th Century, Christianity had arrived, and a wooden St. Paul's Cathedral was founded in AD 604.
London's fortunes revived fully in the late 9th Century when King Alfred the Great defeated Viking invaders and re-fortified the old Roman City around 886 AD, renaming it Lundenburgh. Alfred repaired the ancient walls and built up defences, ensuring that medieval London began to prosper securely within the boundaries of old Londinium.
From that point on, London grew into one of England's most important towns, a centre of commerce and crafts. Its streets were a maze of timber-framed houses and open-air markets, and the River Thames bustled with ships. In the 10th and 11th centuries, the City's influence increased, setting the stage for even greater changes to come.
A significant turning point came in 1066, when the Normans conquered England. After his victory at Hastings, William the Conqueror marched on London and was crowned king at Westminster Abbey. To secure his rule, William built the formidable Tower of London (begun in 1078) at the City's edge – a stone fortress that still stands today as a symbol of Norman power.
Under the Normans and successive medieval kings, London expanded in both size and significance. By the 12th Century, it was England's largest city and de facto capital. Medieval Londoners witnessed the construction of the first London Bridge in stone (opened in the 1200s), a marvel of its time, lined with shops and houses atop its span.
The late medieval period brought both turmoil and growth. In 1348, the Black Death plague swept through London, tragically killing perhaps half the population. Despite this devastation, the City rebounded and continued to grow as a trade hub.
Tensions between social classes flared in events like the Peasants' Revolt of 1381, when rebels from the countryside marched into London, even entering the Tower of London and executing the Archbishop of Canterbury before the uprising was quashed.
The Middle Ages in London effectively came to an end with the Wars of the Roses – a series of dynastic civil wars. When Henry VII seized the throne in 1485, founding the Tudor dynasty, a new chapter in London's story was about to begin.