Known as "Londinium", the Roman legions established a settlement on the current site of the City of London around 43 AD. Its bridge over the River Thames turned the city into a road nexus and major port, serving as a major commercial centre in Roman Britain until its abandonment during the 5th century. Archaeologist Leslie Wallace notes that, because extensive archaeological excavation has not revealed any signs of a significant pre-Roman presence, "arguments for a purely Roman foundation of London are now common and uncontroversial."
At its height, the Roman city had a population of approximately 45,000–60,000 inhabitants. Londinium was an ethnically diverse city, with inhabitants from across the Roman Empire, including natives of Britannia, continental Europe, the Middle East, and North Africa. The Romans built the London Wall some time between 190 and 225 AD. The boundaries of the Roman city were similar to those of the City of London today, though the City extends further west than Londonium's Ludgate, and the Thames was undredged and thus wider than it is today, with Londonium's shoreline slightly north of the City's present shoreline. The Romans built a bridge across the river, as early as 50 AD, near to today's London Bridge.
By the time the London Wall was constructed, the City's fortunes were in decline, and it faced problems of plague and fire. The Roman Empire entered a long period of instability and decline, including the Carausian Revolt in Britain. In the 3rd and 4th centuries, the city was under attack from Picts, Scots, and Saxon raiders. The decline continued, both for Londinium and the Empire, and in 410 AD the Romans withdrew entirely from Britain. Many of the Roman public buildings in Londinium by this time had fallen into decay and disuse, and gradually after the formal withdrawal the city became almost (if not, at times, entirely) uninhabited. The centre of trade and population moved away from the walled Londinium to Lundenwic ("London market"), a settlement to the west, roughly in the modern day Strand/Aldwych/Covent Garden area.
During the Anglo-Saxon Heptarchy, the London area came in turn under the Kingdoms of Essex, Mercia, and later Wessex, though from the mid 8th century it was frequently under the control or threat of the Vikings.
Bede records that in 604 AD St Augustine consecrated Mellitus as the first bishop to the Anglo-Saxon kingdom of the East Saxons and their king, Sæberht. Sæberht's uncle and overlord, Æthelberht, king of Kent, built a church dedicated to St Paul in London, as the seat of the new bishop. It is assumed, although unproven, that this first Anglo-Saxon cathedral stood on the same site as the later medieval and the present cathedrals.
Alfred the Great, King of Wessex and arguably the first king of the "English", occupied and began the resettlement of the old Roman walled area, in 886, and appointed his son-in-law Earl Æthelred of Mercia over it as part of their reconquest of the Viking occupied parts of England. The refortified Anglo-Saxon settlement was known as Lundenburh ("London Fort", a borough). The historian Asser said that "Alfred, king of the Anglo-Saxons, restored the city of London splendidly ... and made it habitable once more." Alfred's "restoration" entailed reoccupying and refurbishing the nearly deserted Roman walled city, building quays along the Thames, and laying a new city street plan.
Alfred's taking of London and the rebuilding of the old Roman city was a turning point in history, not only as the permanent establishment of the City of London, but also as part of a unifying moment in early England, with Wessex becoming the dominant English kingdom and the repelling (to some degree) of the Viking occupation and raids. While London, and indeed England, were afterwards subjected to further periods of Viking and Danish raids and occupation, the establishment of the City of London and the Kingdom of England prevailed.
In the 10th century, Athelstan permitted eight mints to be established, compared with six in his capital, Winchester, indicating the wealth of the city. London Bridge, which had fallen into ruin following the Roman evacuation and abandonment of Londinium, was rebuilt by the Saxons, but was periodically destroyed by Viking raids and storms.
As the focus of trade and population was moved back to within the old Roman walls, the older Saxon settlement of Lundenwic was largely abandoned and gained the name of Ealdwic (the "old settlement"). The name survives today as Aldwych (the "old market-place"), a name of a street and an area of the City of Westminster between Westminster and the City of London.
Map of London in about 1300
Following the Battle of Hastings, William the Conqueror marched on London (reaching as far as Southwark), but failed to get across London Bridge or to defeat the Londoners. He eventually crossed the River Thames at Wallingford, pillaging the land as he went. Rather than continuing the war, Edgar the Ætheling, Edwin of Mercia and Morcar of Northumbria surrendered at Berkhamsted. William granted the citizens of London a charter in 1075; the City was one of a few examples of the English retaining some authority. The City was not covered by the Domesday Book.
William built three castles nearby, to keep Londoners subdued:
About 1130, Henry I granted a sheriff to the people of London, along with control of the county of Middlesex: this meant that the two entities were regarded as one administratively (not that the county was a dependency of the City) until the Local Government Act 1888. By 1141 the whole body of the citizenry was considered to constitute a single community. This 'commune' was the origin of the City of London Corporation and the citizens gained the right to appoint, with the king's consent, a Mayor in 1189—and to directly elect the Mayor from 1215.
From medieval times, the City has been composed of 25 ancient wards, each headed by an Alderman, who chairs Wardmotes, which still take place at least annually. A Folkmoot, for the whole of the City held at the outdoor cross of St Paul's Cathedral, was formerly also held. Many of the medieval offices and traditions continue to the present day, demonstrating the unique nature of the City and its Corporation.
In 1381, the Peasants' Revolt affected London. The rebels took the City and the Tower of London, but the rebellion ended after its leader, Wat Tyler, was killed during a confrontation that included Lord Mayor William Walworth.
The 1666 Great Fire as depicted in a 17th-century painting: it depicts Old London Bridge, churches, houses, and the Tower of London as seen from a boat near Tower Wharf
The City was burnt severely on a number of occasions, the worst being in 1123 and (more famously) in the Great Fire of London in 1666. Both of these fires were referred to as the Great Fire. After the fire of 1666, a number of plans were drawn up to remodel the City and its street pattern into a renaissance-style city with planned urban blocks, squares and boulevards. These plans were almost entirely not taken up, and the medieval street pattern re-emerged almost intact.
Early modern period
By the late 16th century, London increasingly became a major centre for banking, international trade and commerce. The Royal Exchange was founded in 1565 by Sir Thomas Gresham as a centre of commerce for London's merchants, and gained Royal patronage in 1571. Although no longer used for its original purpose, its location at the corner of Cornhill and Threadneedle Street continues to be the geographical centre of the City's core of banking and financial services, with the Bank of England moving to its present site in 1734, opposite the Royal Exchange on Threadneedle Street. Immediately to the south of Cornhill, Lombard Street was the location from 1691 of Lloyd's Coffee House, which became the world-leading insurance market. London's insurance sector continues to be based in the area, particularly in Lime Street.
In 1708, Christopher Wren's masterpiece, St Paul's Cathedral, was completed on his birthday. The first service had been held on 2 December 1697, more than 10 years earlier. It replaced the original St Paul's, which had been completely destroyed in the Great Fire of London, and is considered to be one of the finest cathedrals in Britain and a fine example of Baroque architecture.
Growth of London
The 18th century was a period of rapid growth for London, reflecting an increasing national population, the early stirrings of the Industrial Revolution, and London's role at the centre of the evolving British Empire. The urban area expanded beyond the borders of the City of London, most notably during this period towards the West End and Westminster.
Expansion continued and became more rapid by the beginning of the 19th century, with London growing in all directions. To the East the Port of London grew rapidly during the century, with the construction of many docks, needed as the Thames at the City could not cope with the volume of trade. The arrival of the railways and the Tube meant that London could expand over a much greater area. By the mid-19th century, with London still rapidly expanding in population and area, the City had already become only a small part of the wider metropolis.
19th and 20th centuries
An attempt was made in 1894 with the Royal Commission on the Amalgamation of the City and County of London to end the distinction between the City and the surrounding County of London, but a change of government at Westminster meant the option was not taken up. The City as a distinct polity survived despite its position within the London conurbation and numerous local government reforms. Supporting this status, the City was a special parliamentary borough that elected four members to the unreformed House of Commons, who were retained after the Reform Act 1832; reduced to two under the Redistribution of Seats Act 1885; and ceased to be a separate constituency under the Representation of the People Act 1948. Since then the City is a minority (in terms of population and area) of the Cities of London and Westminster.
The City's population fell rapidly in the 19th century and through most of the 20th century, as people moved outwards in all directions to London's vast suburbs, and many residential buildings were demolished to make way for office blocks. Like many areas of London and other British cities, the City fell victim to large scale and highly destructive aerial bombing during World War II, especially in the Blitz. Whilst St Paul's Cathedral survived the onslaught, large swathes of the area did not and the particularly heavy raids of late December 1940 led to a firestorm called the Second Great Fire of London.
There was a major rebuilding programme in the decades following the war, in some parts (such as at the Barbican) dramatically altering the urban landscape. But the destruction of the older historic fabric allowed the construction of modern and larger-scale developments, whereas in those parts not so badly affected by bomb damage the City retains its older character of smaller buildings. The street pattern, which is still largely medieval, was altered slightly in places, although there is a more recent trend of reversing some of the post-war modernist changes made, such as at Paternoster Square.
The City suffered terrorist attacks including the 1993 Bishopsgate bombing (IRA) and the 7 July 2005 London bombings (Islamist). In response to the 1993 bombing, a system of road barriers, checkpoints and surveillance cameras referred to as the "ring of steel" has been maintained to control entry points to the City.
The 1970s saw the construction of tall office buildings including the 600-foot (183 m), 47-storey Natwest Tower, the first skyscraper in the UK. Office space development has intensified especially in the central, northern and eastern parts, with skyscrapers including 30 St. Mary Axe ("the Gherkin"'), Leadenhall Building ("the Cheesegrater"), 20 Fenchurch Street ("the Walkie-Talkie"), the Broadgate Tower and the Heron Tower, the tallest in the City. Another skyscraper, 22 Bishopsgate, is under construction.
The main residential section of the City today is the Barbican Estate, constructed between 1965 and 1976. The Museum of London is based there, as are a number of other services provided by the Corporation.
For a history of the etymology behind the City's streets see: Street names of the City of London