The area now occupied by the City of Sheffield has been inhabited since at least the late Upper Palaeolithic period (about 12,800 years ago). However, the settlements that developed and amalgamated to form Sheffield are of Anglo-Saxon and Danish origin, dating from the second half of the first millennium. Around this time, the Sheffield area spanned the border between the kingdoms of Mercia and Northumbria.
After the Norman Conquest, Sheffield Castle was built to protect the local settlements, and by 1296 a market was established at what is now Castle Square. Sheffield subsequently expanded to become a small market town, which remains the centre of the modern city.
By the 14th century Sheffield was renowned for knife production, and by the early 1600s had become England's main centre of cutlery manufacture outside of London.
However, the loss of some important export markets led to a recession in the late 18th and early 19th century, and the resulting poor conditions culminated in a cholera epidemic that killed 402 people in 1832.
During the 19th century many steel innovations were discovered locally, including crucible and stainless steel and the Sheffield plate technique. These drove Sheffield's growth as an industrial town, gaining the city an international reputation for its steel production and stimulating an almost tenfold population increase during the Industrial Revolution.
The town's population continued to expand rapidly throughout the 19th century, increasing from 60,095 in 1801 to 451,195 by 1901. The town was incorporated as a borough in 1842 and was granted a city charter in 1893.
To meet the growing population's need for improved water supplies, several new reservoirs were built on the outskirts of the town. In 1864 the dam wall of one of these collapsed, causing the Great Sheffield Flood, in which 270 people were killed and substantial areas of the town devastated.
The influx of people also led to the construction of numerous back-to-back houses, which, along with severe pollution from the factories, inspired George Orwell in 1937 to describe Sheffield as "the ugliest town in the Old World".
As the Second World War impended, Sheffield's steel factories prepared to manufacture weapons and ammunition. This made the city a target for bombing raids, the most severe of which was the Sheffield Blitz on the nights of 12th and 15th December 1940, in which 660 people died and many buildings were destroyed.
In the 1950s and '60s, many of the city's slums were pulled down and replaced with housing schemes such as the Park Hill flats. Much of the city centre was also cleared to make way for a new road system.
During the 1970s and '80s, increased automation and international competition in iron and steel triggered a decline in traditional local industries. This coincided with the collapse of coal mining in the area.
In 1990, construction of the Meadowhall shopping centre on the site of a former steelworks was a mixed blessing, creating much-needed jobs but accelerating the decline of the city centre.
Regeneration efforts were boosted when the city hosted the 1991 World Student Games, for which several new sporting facilities were created. These include the Sheffield Arena, Don Valley Stadium and the Ponds Forge complex, all of which are still used for international sporting events.
The 21st century has seen extensive redevelopment in Sheffield, which is changing rapidly as new projects regenerate some of the more run-down parts of the city.
One such example is the Heart of the City Project, which has initiated several public works in the city centre, including the Peace Gardens, the Millennium Galleries, the Winter Gardens and the Millennium Square (a public space to link these areas).
Further developments have included the modernising of Sheaf Square, in front of the recently revamped railway station. The new square contains The Cutting Edge, a sculpture made from Sheffield steel.