The 21 most influential cities in the world

Technology lives in San Francisco, which is just a stones throw from the headquarters of Facebook, Google, and many other tech giants.

Home to the main financial centre on the Chinese mainland, Shanghai is also the world's busiest container port, making it a global hub for all kinds of trade.

It may not be as well known as it's American neighbours, but Toronto is a globally important city, and has the world's seventh-largest stock exchange by market capitalisation.

The lower ranked of two Australian cities to make this list, Melbourne was ranked as the top place for international students.

Germany is Europe's biggest power, so it makes sense that it's capital is among the world's most influential cities. Berlin's best performance in the Global Cities Index is from the business activity sector.

Perhaps the most important city in the southern hemisphere, Sydney is Australia's main city for commerce and finance, and links the English speaking world to Asia.

Capital of the largest country in the world and a major hub for Russia's huge commodity industry. According to Global Cities Index, it is also the best place in the world to visit museums.

A major hub for commerce in the Spanish speaking world, Madrid scored highly in the business activity category.

As tensions rose in the Korean Peninsula last year, South Korea's capital grew significantly in global importance. It is also a major commerce hub, and home to major brands including Samsung.

There is an argument to say that Washington is the world's most influential city, given it is home to all of America's important political institutions. Home to the president, Congress, and international institutions including the World Bank and International Monetary Fund, Washington is a city of huge influence.

Politics and bureaucracy dominate the agenda in Belgium's capital, the home of the European Union. Relatively small compared to many major cities, it punches well above its weight thanks to the EU.

The capital and political hub of the world's second largest economy is understandably influential. It is also home to more companies in the Global Fortune 500 than any other city.

Trading defines Chicago's importance as a major international city, with two of the biggest commodity exchanges based there. Agricultural products like wheat, corn and pork are among the products that are traded on the city's mercantile exchanges.

Finance and shipping reign supreme in this Asian city state. Singapore's container port is one of the world's largest. It is also a major hub for the oil industry — almost half of all oil consumed in the world passes through Singapore.

Home to Hollywood, LA means showbiz, with movie studios, TV stations and more based in the California mega city. It's location on the USA's west coast also makes it a key hub for trade with Asia.

Formerly controlled by Britain, Hong Kong was handed back to China in 1997, and as such has a unique place in the world. One of Asia's biggest financial centres, it is also a major port city.

Japan's sprawling capital, home to nearly 40 million people in its metropolitan area, is one of the best educated cities on the planet, with a high proportion of people with tertiary degrees.

Art and fashion make their home in France's capital, which is also the best city in the world for the exchange of information, according to the Global Cities Index.

Brexit may be likely to marginally diminish London's role as a global centre, but for now it remains the world's second most influential city. Home to Europe's financial hub in the City, London is vital for the world economy.

It's no surprise that New York, home of President Donald Trump, Wall Street, and the United Nations, is the world's most important city.