The City of London, one of the largest financial centres in the world
London's gross regional product in 2017 was £430 billion, around a quarter of UK GDP, while the economy of the London metropolitan area—the largest in Europe—generates about 1/3 of the UK's GDP (almost $700 billion in 2005). London has five major business districts: the City, Westminster, Canary Wharf, Camden & Islington and Lambeth & Southwark. One way to get an idea of their relative importance is to look at relative amounts of office space: Greater London had 27 million m2 of office space in 2001, and the City contains the most space, with 8 million m2 of office space. London has some of the highest real estate prices in the world. London is the world's most expensive office market for the last three years according to world property journal (2015) report. As of 2015 the residential property in London is worth $2.2 trillion – same value as that of Brazil's annual GDP. The city has the highest property prices of any European city according to the Office for National Statistics and the European Office of Statistics. On average the price per square metre in central London is €24,252 (April 2014). This is higher than the property prices in other G8 European capital cities; Berlin €3,306, Rome €6,188 and Paris €11,229.
London's finance industry is based in the City of London and Canary Wharf, the two major business districts in London. London is one of the pre-eminent financial centres of the world as the most important location for international finance. London took over as a major financial centre shortly after 1795 when the Dutch Republic collapsed before the Napoleonic armies. For many bankers established in Amsterdam (e.g. Hope, Baring), this was only time to move to London. The London financial elite was strengthened by a strong Jewish community from all over Europe capable of mastering the most sophisticated financial tools of the time. This unique concentration of talents accelerated the transition from the Commercial Revolution to the Industrial Revolution. By the end of the 19th century, Britain was the wealthiest of all nations, and London a leading financial centre. Still, as of 2016 London tops the world rankings on the Global Financial Centres Index (GFCI), and it ranked second in A.T. Kearney's 2018 Global Cities Index.
London's largest industry is finance, and its financial exports make it a large contributor to the UK's balance of payments. Around 325,000 people were employed in financial services in London until mid-2007. London has over 480 overseas banks, more than any other city in the world. It is also the world's biggest currency trading centre, accounting for some 37 per cent of the $5.1 trillion average daily volume, according to the BIS. Over 85 per cent (3.2 million) of the employed population of greater London works in the services industries. Because of its prominent global role, London's economy had been affected by the financial crisis of 2007–2008. However, by 2010 the City has recovered; put in place new regulatory powers, proceeded to regain lost ground and re-established London's economic dominance. Along with professional services headquarters, the City of London is home to the Bank of England, London Stock Exchange, and Lloyd's of London insurance market.
Over half of the UK's top 100 listed companies (the FTSE 100) and over 100 of Europe's 500 largest companies have their headquarters in central London. Over 70 per cent of the FTSE 100 are within London's metropolitan area, and 75 per cent of Fortune 500 companies have offices in London.
Media and technology
Media companies are concentrated in London and the media distribution industry is London's second most competitive sector. The BBC is a significant employer, while other broadcasters also have headquarters around the City. Many national newspapers are edited in London. London is a major retail centre and in 2010 had the highest non-food retail sales of any city in the world, with a total spend of around £64.2 billion. The Port of London is the second-largest in the United Kingdom, handling 45 million tonnes of cargo each year.
A growing number of technology companies are based in London notably in East London Tech City, also known as Silicon Roundabout. In April 2014, the city was among the first to receive a geoTLD. In February 2014 London was ranked as the European City of the Future  in the 2014/15 list by FDi Magazine.
London is one of the leading tourist destinations in the world and in 2015 was ranked as the most visited city in the world with over 65 million visits. It is also the top city in the world by visitor cross-border spending, estimated at US$20.23 billion in 2015. Tourism is one of London's prime industries, employing the equivalent of 350,000 full-time workers in 2003, and the city accounts for 54% of all inbound visitor spending in the UK. As of 2016 London is the world top city destination as ranked by TripAdvisor users.
In 2015 the top most-visited attractions in the UK were all in London. The top 10 most visited attractions were: (with visits per venue)