London is the capital of both England and the United Kingdom. It has been an influential city for two millennia, and its history goes back to its founding by the Romans, then named Londinium. London's core, the ancient City of London, the 'square mile', retains its medieval boundaries. However, since at least the nineteenth century, the name "London" has also referred to the whole metropolis that has developed around it. Today, the bulk of this conurbation forms the London region and the Greater London administrative area, with its own elected mayor and assembly.
London is a preeminent global city and one of the world's largest financial centres.Central London is home to the headquarters of more than half of the UK's top 100 listed companies and more than 100 of Europe's 500 largest. London's influence in politics, education, entertainment, media, fashion, the arts and culture in general contributes to its global position. It is a major tourist destination for both domestic and overseas visitors. London hosted the 1908 and 1948 Summer Olympics and will host the 2012 Summer Olympics.
London contains four World Heritage Sites: the Tower of London; the historic settlement of Greenwich; the Royal Botanic Gardens, Kew; and the site comprising the Palace of Westminster, Westminster Abbey and St. Margaret's Church.
London has a wide range of peoples, cultures, and religions, and more than 300 languages are spoken within its boundaries. In July 2007, it had an official population of 7,556,900 within the boundaries of Greater London, making it the most populous municipality in the European Union. The Greater London Urban Area (the second largest in the EU) has a population of 8,278,251. while the metropolitan area (the largest in the EU) has an estimated total population of between 12 million and 14 million. The public transport network, administered by Transport for London, is the most extensive in the world, London Heathrow Airport is the world's busiest airport by number of international passengers and the airspace is the busiest of any urban centre in the world.
The etymology of London remains a mystery. The earliest etymological explanation can be attributed to Geoffrey of Monmouth in Historia Regum Britanniae. The name is described as originating from King Lud, who had allegedly taken over the city and named it Kaerlud. This would have had a derivational form Kaerludein, which, by aphaeresis, eventually developed as London. Many other theories have been advanced over the centuries, most of them deriving the name from the Welsh or British languages. It is also believed the name "London" comes from the celtic word "Lyndon", which means "shadowy waters", referring to the Thames River.
Although there is evidence of scattered Brythonic settlements in the area, the first major settlement was founded by the Romans in 43 AD as Londinium, following the Roman conquest of Britain. This Londinium lasted for just seventeen years. Around 61, the Iceni tribe led by Queen Boudica stormed this first London, burning it to the ground. The next, heavily planned incarnation of the city prospered and superseded Colchester as the capital of the Roman province of Britannia in 100. At its height in the 2nd century, Roman London had a population of around 60,000.