Although there is some evidence of scattered pre-Roman settlement in the area, the first major settlement
was founded by the Romans in AD 43, following the Roman invasion of Britain. This settlement was called Londinium, commonly believed to be the origin of the present-day name, although a Celtic origin is also possible.
The first London lasted for just seventeen years. Around AD 61, the Iceni tribe of Celts led by Queen Boudica stormed London, burning it to the ground. The next, heavily-planned incarnation of the city prospered and superseded
Colchester as the capital of the Roman province of Britannia in AD 100. However, by the 3rd century AD, the city started a slow decline due to trouble in the Roman Empire, and by the 5th century AD, it was abandoned.
By 600 AD, the Anglo-Saxons had created a new settlement (Lundenwic) about 1km upstream from the old Roman city, around what is now Covent Garden. There was probably a harbour at the mouth of the River Fleet for fishing and trading, and this trading grew until disaster struck in 851 AD, when the new city's ramshackle
defences were overcome by a massive Viking raid and it was razed to the ground. A Viking occupation twenty years later was short-lived, and Alfred the Great, the new King of England, established peace and moved the settlement within the defensive walls of the old Roman
city (then called Lundenburgh). The original city became Ealdwīc ("old city"), a name surviving to the present day as Aldwych.
Subsequently, under the control of various English kings, London once again prospered as an international
trading centre and political arena. However, Viking raids began again in the late 10th century, and reached a head in 1013
when they besieged the city under Danish King Canute and forced English King Aethelred the Unready to flee. In a retaliatory attack, Aethelred's army achieved victory by pulling down London Bridge with the Danish garrison on top, and English control was re-established.
Canute took control of the English throne in 1017, controlling the city and country until 1042, when his death
resulted in a reversion to Anglo-Saxon control under his pious step-son Edward the Confessor, who re-founded Westminster Abbey and the adjacent Palace of Westminster. By this time, London had become the largest and most prosperous city in England, although the official seat
of government was still at Winchester.
Norman and medieval London
Following a victory at the Battle of Hastings, William the Conqueror, the then Duke of Normandy, was crowned King of England in the newly-finished Westminster Abbey on Christmas Day 1066. William granted the citizens of London special privileges, whilst building a castle in the southeast corner
of the city to keep them under control. This castle was expanded by later kings and is now known as the Tower of London, serving first as a royal residence and later as a prison.
In 1097, William II began the building of Westminster Hall, close by the abbey of the same name. The hall proved the basis of a new Palace of Westminster, the prime royal residence throughout the Middle Ages. Westminster became the seat of the royal court and government
(persisting until the present day), whilst its distinct neighbour, the City of London, was a centre of trade and commerce
and flourished under its own unique administration, the Corporation of London. Eventually, the adjacent cities grew together and formed the basis of modern central London, superseding Winchester as capital of England in the 12th century.
After the successful defeat of the Spanish Armada in 1588, political stability in England allowed London to grow further. In 1603, James I came to the thrones of both England and Scotland, essentially uniting the two countries. His enactment of harsh
anti-Catholic laws made him unpopular, and an assassination attempt was made on 5 November 1605 — the famous Gunpowder Plot.
Plague caused extensive problems for London in the early 17th century, culminating in the Great Plague in 1665-1666. This was the last major outbreak in Europe, possibly thanks to the disaster that immediately followed
in 1666. A fire (the Great Fire of London) broke out in the original City and quickly swept through London's wooden buildings, destroying large swathes
of the city (and killing off much of the disease-carrying rat population). Rebuilding took over ten years.
Rise of modern London
London's growth accelerated in the 18th century, and was the world's largest city from about 1831 to 1925.
This growth was aided from 1836 by London's first railways which put small countryside towns within easy reach of the city. The rail network expanded very rapidly, and
caused these places to grow whilst London itself expanded into surrounding fields, merging with neighbouring settlements such
as Kensington. Rising traffic congestion on city centre roads led to the creation of the world's first metro system — the London Underground — in 1863, driving yet further expansion and urbanisation.
London's local government system struggled to cope with the rapid growth, especially in providing the city
with adequate infrastructure. Between 1855 and 1889, the Metropolitan Board of Works oversaw infrastructure expansion. It was then replaced by the County of London, overseen by the London County Council, London's first elected city-wide administration.
The Blitz and other bombing by the German Luftwaffe during World War II killed over 30,000 Londoners and flattened large tracts of housing and other buildings across London. The rebuilding
during the 1950s, 1960s and 1970s was characterised by a wide range of architectural styles and has resulted in a lack of architectural unity that has become part of London's character. In the same period,
extensive immigration, primarily from the Commonwealth, changed the demographic mix of the city. In 1965 London's political boundaries were expanded to take into account
the growth of the urban area outside the County of London's borders. The expanded region was called Greater London and was administered by the Greater London Council.
An economic revival from the 1980s onwards re-established London's position as an eminent trading centre.
However, as the seat of government and the most important city in the UK, it has been subjected to bouts of terrorism. IRA bombers sought to pressure the government into negotiations over Northern Ireland, frequently disrupting city activities with bomb threats — some of which were carried out — until
their 1997 ceasefire. More recently, a series of coordinated bomb attacks were carried out by Islamic extremist suicide bombers on the public transport network — just 24 hours after London was awarded the 2012 Summer Olympics.