Sheffield is a city and metropolitan borough in South Yorkshire, England. Historically part of the West Riding of Yorkshire, its name derives from the River Sheaf, which runs through the city. With some of its southern suburbs annexed from Derbyshire, the city has grown from its largely industrial roots to encompass a wider economic base. The population of the City of Sheffield is 563,749 and it is one of the eight largest regional English cities that make up the Core Cities Group. Sheffield is the third largest English district by population. The metropolitan population of Sheffield is 1,569,000.
In the 19th century, Sheffield gained an international reputation for steel production. Many innovations were developed locally, including crucible and stainless steel, fuelling an almost tenfold increase in the population in the Industrial Revolution.
The 21st century has seen extensive redevelopment in Sheffield along with other British cities. Sheffield's gross value added (GVA) has increased by 60% since 1997, standing at £9.2 billion in 2007. The economy has experienced steady growth averaging around 5% annually.
The city is in the eastern foothills of the Pennines, and the valleys of the River Don and its four tributaries, the Loxley, the Porter Brook, the Rivelin and the Sheaf. 61% of Sheffield's entire area is green space, and a third of the city lies within the Peak District national park. There are more than 250 parks, woodlands and gardens in the city, with an often quoted estimated 2 million trees, and claims of Sheffield having the highest ratio of trees to people of any city in Europe.
By 1296, a market had been established at what is now known as Castle Square, and Sheffield subsequently grew into a small market town. In the 14th century, Sheffield was already noted for the production of knives, as mentioned in Geoffrey Chaucer's The Canterbury Tales, and by the early 1600s it had become the main centre of cutlery manufacture in England outside London, overseen by the Company of Cutlers in Hallamshire. From 1570 to 1584, Mary, Queen of Scots, was imprisoned in Sheffield Castle and Sheffield Manor.
During the 1740s, a form of the crucible steel process was discovered that allowed the manufacture of a better quality of steel than had previously been possible. In about the same period, a technique was developed for fusing a thin sheet of silver onto a copper ingot to produce silver plating, which became widely known as Sheffield plate. These innovations spurred Sheffield's growth as an industrial town, but the loss of some important export markets led to a recession in the late 18th and early 19th century.
Sheffield is changing rapidly as new projects regenerate some of the more run-down parts of the city. One such, the Heart of the City Project, has initiated a number of public works in the city centre: the Peace Gardens were renovated in 1998, the Millennium Galleries opened in April 2001, the Winter Gardens were opened in May 2003, and a public space to link these two areas, the Millennium Square, was opened in May 2006. Additional developments included the remodelling of Sheaf Square, in front of the recently refurbished railway station. The new square contains "The Cutting Edge", a sculpture designed by Si Applied Ltd and made from Sheffield steel.