London Bridge

Coordinates: 51°30′29″N 0°05′16″W / 51.50806°N 0.08778°W / 51.50806; -0.08778

Several historical bridges named London Bridge have spanned the River Thames between the City of London and Southwark, in central London. The current crossing, which opened to traffic in 1974, is a box girder bridge built from concrete and steel. This replaced a 19th-century stone-arched bridge, which in turn superseded a 600-year-old medieval structure. This was preceded by a succession of timber bridges, the first built by the Roman founders of London.

The current bridge stands at the western end of the Pool of London but is positioned 30 metres (98 ft) upstream from previous alignments. The traditional ends of the medieval bridge were marked by St Magnus-the-Martyr on the northern bank and Southwark Cathedral on the southern shore. Until Putney Bridge opened in 1729, London Bridge was the only road-crossing of the Thames downstream of Kingston-upon-Thames. Its importance has been the subject of popular culture throughout the ages such as in the nursery rhyme "London Bridge Is Falling Down" and its inclusion within art and literature.

London

London ⁱ/ˈlʌndən/ is the capital and most populous city of England and the United Kingdom. Standing on the River Thames, London has been a major settlement for two millennia. It was founded by the Romans, who named it Londinium. London's ancient core, the City of London, largely retains its 1.12-square-mile (2.9 km²) medieval boundaries and in 2011 had a resident population of 7,375, making it the smallest city in England. Since at least the 19th century, the term London has also referred to the metropolis developed around this core. The bulk of this conurbation forms Greater London, a region of England governed by the Mayor of London and the London Assembly. The conurbation also covers two English counties: the small district of the City of London and the county of Greater London. The latter constitutes the vast majority of London, though historically it was split between Middlesex (a now abolished county), Essex, Surrey, Kent and Hertfordshire.

Tower Bridge

Coordinates: 51°30′20″N 0°04′32″W / 51.50556°N 0.07556°W / 51.50556; -0.07556

Tower Bridge (built 1886–1894) is a combined bascule and suspension bridge in London. The bridge crosses the River Thames close to the Tower of London and has become an iconic symbol of London. Tower Bridge is one of five London bridges now owned and maintained by the Bridge House Estates, a charitable trust overseen by the City of London Corporation. It is the only one of the Trust's bridges not to connect the City of London directly to the Southwark bank, as its northern landfall is in the Tower Hamlets.

The bridge consists of two bridge towers tied together at the upper level by two horizontal walkways, designed to withstand the horizontal tension forces exerted by the suspended sections of the bridge on the landward sides of the towers. The vertical components of the forces in the suspended sections and the vertical reactions of the two walkways are carried by the two robust towers. The bascule pivots and operating machinery are housed in the base of each tower. The bridge's present colour scheme dates from 1977, when it was painted red, white and blue for Queen Elizabeth II's Silver Jubilee.

Bridge

A bridge is a structure built to span physical obstacles without closing the way underneath such as a body of water, valley, or road, for the purpose of providing passage over the obstacle. There are many different designs that each serve a particular purpose and apply to different situations. Designs of bridges vary depending on the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, the material used to make it, and the funds available to build it.

Etymology

The Oxford English Dictionary traces the origin of the word bridge to an Old English word brycg, of the same meaning. The word can be traced directly back to Proto-Indo-European *bʰrēw-. The word for the card game of the same name has a different origin.

History

The first bridges made by humans were probably spans of cut wooden logs or planks and eventually stones, using a simple support and crossbeam arrangement. Some early Americans used trees or bamboo poles to cross small caverns or wells to get from one place to another. A common form of lashing sticks, logs, and deciduous branches together involved the use of long reeds or other harvested fibers woven together to form a connective rope capable of binding and holding together the materials used in early bridges.

United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a sovereign state in the European Union. Lying off the north-western coast of the European mainland, it includes the island of "Great Britain" (a term also applied loosely to refer to the whole country), the north-eastern part of the island of Ireland and many smaller islands.Northern Ireland is the only part of the UK that shares a land border with another state—the Republic of Ireland. Apart from this land border, the UK is surrounded by the Atlantic Ocean, with the North Sea to its east, the English Channel to its south and the Celtic Sea to its south-southwest. The Irish Sea lies between Great Britain and Ireland. With an area of 93,800 square miles (243,000 km²), the UK is the 80th-largest sovereign state in the world and the 11th-largest in Europe. It is also is the 21st-most populous country, with an estimated 64.5 million inhabitants.

The United Kingdom is a constitutional monarchy with a parliamentary system of governance. Its capital city is London, an important global city and financial centre with an urban population of 10,310,000, the fourth-largest in Europe and second-largest in the European Union. The current monarch—since 6 February 1952—is Queen Elizabeth II. The UK consists of four countries: England, Scotland, Wales, and Northern Ireland. The latter three have devolved administrations, each with varying powers, based in their capitals, Edinburgh, Cardiff, and Belfast, respectively. The nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the United Kingdom, being Crown dependencies with the British Government responsible for defence and international representation.