In the 2011 census, the population of the Leicester unitary authority was 330,000, making it the largest unitary authority in the East Midlands region, whilst 509,000 people lived in the wider Leicester Urban Area, making Leicester the tenth largest city in the United Kingdom and England's eleventh largest urban area. It is the largest city and has the second largest urban area in the East Midlands region. Eurostat's Larger Urban Zone listed the population of Leicester LUZ at 836,484 (2011). According to the 2011 census Leicester had the largest proportion of people aged 19-and-under in the East Midlands with 27 per cent.
"Unlike almost every other city in the UK, Leicester has retained a remarkable record of its past in buildings that still stand today". Ancient Roman pavements and baths remain in Leicester from its early settlement as Ratae, a Roman military outpost in a region inhabited by the Celtic Corieltauvi tribe. Following the Roman withdrawal from Britain, the early medieval Ratae is shrouded in obscurity, but when the settlement was captured by the Danes it became one of five fortified towns important to the Danelaw and it appeared in the Domesday Book as "Ledecestre". Leicester continued to grow throughout the Early Modern period as a market town, although it was the Industrial Revolution that facilitated a process of rapid unplanned urbanisation in the area.
A newly constructed rail and canal network routed through the area stimulated industrial growth in the 19th century, and Leicester became a major economic centre with a variety of manufacturers engaged in engineering, shoemaking and hosiery production. The economic success of these industries, and businesses ancillary to them, resulted in significant urban expansion into the surrounding countryside. Leicester is one of the oldest cities in England, it was the centre of the bishopric from around 670, endowing it with city status. However, it lost city status in the 11th century during a time of struggle between the church and the aristocracy. The boundaries of Leicester were extended several times in the 19th and 20th centuries; it became a county borough in 1889, and was re-granted city status in 1919.
Today, Leicester is located at the intersection of the north/south Midland Main Line and east/west Birmingham/Leicester/Cambridge CrossCountry railway lines and at the confluence of the M1 / M69 motorways and the A46 / A6 trunk routes. The city and metropolitan area is culturally diverse, with well established South Asian and Afro-Caribbean communities, in addition to more recent influxes from European Community countries, amongst others. Leicester is a major centre of learning: the University of Leicester is famous for the quality of its teaching and research; De Montfort University is very well regarded in many of its specialist fields. The city region also hosts many other notable institutions of higher and further education.
On 13 November 2014 Leicester City Council passed a motion resolving to "..boycott any produce originating from illegal Israeli settlements in the West Bank until such time as it complies with international law and withdraws from Palestinian Occupied territories."
Leicester is one of the oldest cities in England, with a history going back at least two millennia. The native Iron Age settlement encountered by the Romans at the site seems to have developed in the 2nd or 1st centuries . Little is known about this settlement or the condition of the River Soar at this time, although roundhouses from this era have been excavated and seem to have clustered along roughly of the east bank of the Soar above its confluence with the Trent. This area of the Soar was split into two channels: a main stream to the easts and a narrower channel on the west, with a presumably marshy island between. The settlement seems to have controlled a ford across the larger channel. The later Roman name was a latinate form of the Brittonic word for "ramparts" (cf. Gaelic rath & the nearby villages of Ratby and Ratcliffe), suggesting the site was an oppidum. The plural form of the name suggests it was initially composed of several villages. The Celtic tribe holding the area was later recorded as the "Coritanians" but an inscription recovered in 1983 showed this to have been a corruption of the original "Corieltauvians".) The Corieltauvians are believed to have ruled over roughly the area of the East Midlands.
It is believed that the Romans arrived in the Leicester area around 47, during their conquest of southern Britain. The Corieltauvian settlement lay near a bridge on the Fosse Way, a Roman road between the legionary camps at Isca (Exeter) and Lindum (Lincoln). It remains unclear whether the Romans fortified and garrisoned the location, but it slowly developed from around the year 50 onwards as the tribal capital of the Corieltauvians under the name Ratae Corieltauvorum. In the 2nd century, it received a forum and bathhouse. In 2013, the discovery of a Roman cemetery found just outside the old city walls and dating back to 300 was announced. The remains of the baths of Roman Leicester can be seen at the Jewry Wall; recovered artifacts are displayed at the adjacent museum.
Knowledge of the town following the Roman withdrawal from Britain is limited. Certainly there is some continuation of occupation of the town, though on a much reduced scale in the 5th and 6th centuries. Its memory was preserved as the  of the History of the Britons. Following the Saxon invasion of Britain, Leicester was occupied by the Middle Angles and subsequently administered by the kingdom of Mercia. It was elevated to a bishopric in either 679 or 680; this see survived until the 9th century, when Leicester was captured by Danish Vikings. Their settlement became one of the Five Burghs of the Danelaw, although this position was short-lived. The Saxon bishop, meanwhile, fled to Dorchester-on-Thames and Leicester did not become a bishopric again until the Church of became Leicester Cathedral in 1927. The settlement was recorded under the name Ligeraceaster in the early 10th century.
Following the Norman conquest, Leicester was recorded by William's Domesday Book as Ledecestre. It was noted as a city (civitas) but lost this status in the 11th century owing to power struggles between the Church and the aristocracy and did not become a legal city again until 1919.
Geoffrey of Monmouth composed his pseudohistorical History of the Kings of Britain around the year 1136, mentioning the town and its King Leir. Geoffrey claimed Cordelia had buried her father beneath the river in a chamber dedicated to Janus and that his feast day was an annual celebration. William Shakespeare's King Lear was loosely based on this story and there is now a statue of Lear in Watermead Country Park.
At the end of the War of the Roses, King Richard III was buried in Leicester's Greyfriars Church, whose ruins are now located beneath a car park. (A plaque in his honor was installed in the central nave of in 1980, but the cathedral has no other connection with him.) There was a legend that his corpse was exhumed by Henry VII and cast into the river, while some historians argued that his tomb and remains were destroyed during the dissolution of the monasteries under Henry VIII. However, in September 2012, an archaeological investigation discovered a skeleton which was subsequently verified to be related to two descendants of Richard III's sister.
On 4 November 1530, Cardinal Thomas Wolsey was arrested on charges of treason and taken from York Place. On his way south to face dubious justice at the Tower of London, he fell ill. The group escorting him was concerned enough to stop at Leicester. There, Wolsey's condition quickly worsened. He died on 29 November 1530 and was buried at Leicester Abbey, now Abbey Park.
Leicester was a Roundhead stronghold during the English Civil War. In 1645, Prince Rupert decided to attack the city to draw the New Model Army away from the Royalist headquarters of Oxford. Royalist guns were set up on Raw Dykes and, after an unsatisfactory response to a demand for surrender, the Newarke was stormed and the city was sacked on 30 May. Hundreds of people were killed by Rupert's cavalry and reports of the severity of the sacking were further exaggerated by the Parliamentary press in London.
The construction of the Grand Union Canal in the 1790s linked Leicester to London and Birmingham; by 1832, the railway had arrived in Leicester. The Leicester and Swannington provided a supply of coal to the town from nearby collieries and the Midland Counties linked the town to the national network by 1840. A direct link to London's St Pancras Station was established by the Midland Main Line in the 1860s. These developments encouraged and accompanied a process of industrialisation which intensified throughout the reign of Queen Victoria. Factories began to appear, particularly along the canal and river, and districts such as Frog Island and Woodgate were the locations of numerous large mills. Between 1861 and 1901, Leicester's population increased from to and the proportion employed in trade, commerce, building, and the city's new factories and workshops rose steadily. Hosiery, textiles, and footwear became the major industrial employers: manufacturers such as N. Corah & Sons and the Cooperative Boot and Shoe Company were opening some of the largest manufacturing premises in Europe. They were joined, in the latter part of the century, by engineering firms such as Kent Street's Taylor & Hubbard (crane makers & founders), Vulcan Road's William Gimson & Company (steam boilers & founders), and Martin Street's Richards & Company (steel works & founders).
The politics of Victorian Leicester were lively and very often bitter. Years of consistent economic growth meant that living standards generally increased, but Leicester was a stronghold of Radicalism. Thomas Cooper, the Chartist, kept a shop in Church Gate. There were serious Chartist riots in the town in 1842 and again six years later. The Leicester Secular Society was founded in 1851 but secularist speakers such as George Holyoake were often denied the use of speaking halls. It was not until 1881 that Leicester Secular Hall was opened. The second half of the 19th century also witnessed the creation of many other institutions, including the town council, the Royal Infirmary, and the Leicester Constabulary. It also benefited from general acceptance that municipal organisations had a responsibility to provide for the town's water supply, drainage, and sanitation.
Leicester became a county borough in 1889, although it was abolished with the rest in 1974 as part of the Local Government Act. The city regained its unitary status apart from Leicestershire in 1997. The borough had been expanding throughout the 19th century, but grew most most notably when it annexed Belgrave, Aylestone, North Evington, Knighton, and Stoneygate in 1892.
In 1900, the Great Central Railway provided another link to London, but the rapid population growth of the previous decades had already begun to slow by the time of Queen Victoria's death in 1901. World War I and the subsequent epidemics had further impacts. Nonetheless, Leicester was finally recognised as a legal city once more in 1919 and, in 1925, again became a cathedral city on the consecration of . It obtained its current boundaries in 1935, with the annexation of the remainder of Evington, Humberstone, Beaumont Leys, and part of Braunstone.
Leicester's diversified economic base and lack of dependence on primary industries meant that it was much better placed than many other cities to weather the tariff wars of the 1920s and Great Depression of the 1930s. The Bureau of Statistics of the newly formed League of Nations identified Leicester in 1936 as the 2nd-richest city in Europe and it became an attractive destination for refugees fleeing persecution and political turmoil in continental Europe. Firms such as Corah and Liberty Shoes used their reputation for producing high-quality products to expand their businesses. These years witnessed the growth in the city of trade unionism and particularly the co-operative movement. The Co-op became an important employer and landowner; when Leicester played host to the Jarrow March on its way to London in 1936, the Co-op provided the marchers with a change of boots. In 1938, Leicester was selected as the base for Squadron 1F, the first A.D.C.C (Air Defence Cadet Corp), the predecessor of the Air Training Corps.
The years after World War II, particularly from the 1960s onwards, brought many social and economic challenges.
Mass housebuilding continued across Leicester for some 30 years after 1945. Existing housing estates such as Braunstone were expanded, while several completely new estates – of both private and council tenure – were built. The last major development of this era was Beaumont Leys in the north of the city, which was developed in the 1970s as a mix of private and council housing. There was a steady decline in Leicester's traditional manufacturing industries and, in the city centre, working factories and light industrial premises have now been almost entirely replaced. Many former factories, including some on Frog Island and at Donisthorpe Mill, have been badly damaged by fire. Rail and barge were finally eclipsed by automotive transport in the 1960s and '70s: the Great Central and the Leicester & Swannington both closed and the northward extension of the M1 motorway linked Leicester into England's growing motorway network. With the loss of much of the city's industry during the 1970s and '80s, some of the old industrial jobs were replaced by new jobs in the service sector, particularly in retail. The opening of the Haymarket Shopping Centre in 1971 was followed by a number of new shopping centres in the city, including St Martin's Shopping Centre in 1984 and the Shire Shopping Centre in 1992. The Shires was subsequently expanded in September 2008 and rebranded as Highcross. By the 1990s, as well, Leicester's central position and good transport links had established it as a distribution centre; the southwestern area of the city has also attracted new service and manufacturing businesses.
Since the war, Leicester has experienced large scale immigration from across the world. Immigrant groups today make up around 40% of Leicester's population, making Leicester one of the most ethnically diverse cities in the United Kingdom. Many Polish servicemen were prevented from returning to their homeland after the war by the communist regime, and they established a small community in Leicester. Economic migrants from the Irish Republic continued to arrive throughout the post war period. Immigrants from the Indian sub-continent began to arrive in the 1960s, their numbers boosted by Asians arriving from Kenya and Uganda in the early 1970s.
In 1972, Idi Amin announced that the entire Asian community in Uganda had 90 days to leave the country. Shortly thereafter, the Leicester City Council launched a campaign aimed at dissuading Ugandan Asians from migrating to the city. The ads did not have their intended effect, instead making more migrants aware of the possibility of settling in Leicester. Nearly a quarter of initial Ugandan refugees (around 5000 to 6000) settled in Leicester, and by the end of the 1970s around another quarter of the initially dispersed refugees had made their way to Leicester. Officially, the adverts were taken out for fear that immigrants to Leicester would place pressure on city services and at least one person who was a city councillor at the time says that he believes they were placed for racist reasons. The initial advertisement was widely condemned, and taken as a marker of anti-Asian sentiment throughout Britain as a whole, although the attitudes that resulted in the initial advertisement were changed significantly in subsequent decades. Recent Leicester councillors have expressed significant regret for the council having run the advertisement.
In the 1990s, a group of Dutch citizens of Somali origin settled in the city. Since the 2004 enlargement of the European Union a significant number of East European migrants have settled in the city. While some wards in the northeast of the city are more than 70% South Asia, wards in the west and south are all over 70% white. The Commission for Racial Equality (CRE) had estimated that by 2011 Leicester would have approximately a 50% ethnic minority population, making it the first city in Britain not to have a white British majority. This prediction was based on the growth of the ethnic minority populations between 1991 (Census 1991 28% ethnic minority) and 2001 (Census 2001 – 36% ethnic minority). However Professor Ludi Simpson at the University of Manchester School of Social Sciences said in September 2007 that the CRE had "made unsubstantiated claims and ignored government statistics" and that Leicester's immigrant and minority communities disperse to other places. The Leicester Multicultural Advisory Group is a forum, set up in 2001 by the editor of the Leicester Mercury, to co-ordinate community relations with members representing the council, police, schools, community and faith groups, and the media.