Its empire came to consist of a federation of cities – stretching from Spain and Scotland in the west, to the Euphrates river in the east – each of which had a territory attached. The first European city to develop networks akin to those of a modern global city was Rome.

As historian Peter Frankopan, author of The Silk Roads, notes: “We think of globalisation as a uniquely modern phenomenon, yet 2,000 years ago it was a fact of life – one that presented opportunities, created problems, and prompted technological advance.”

Within a few hundred years, the world had been effectively shrunk by the growing sophistication of the trade network. Silk even became an international currency. As China began to expand its horizons, the trade in horses, silk, bamboo, rice and wine was vigorous and often used in diplomacy to guarantee peace between empires and cities. One important lesson to be drawn from the early waves of urbanisation and the long distance activities of cities is that prized assets and luxury possessions have often been drivers of interconnection and collaboration. With their deep-rooted cultures and external orientation, they exhibited many of the hallmarks of what are now considered to be global cities.

These cities formed the epicentre of a vast trade network based on a common cultural and linguistic community, and built infrastructure to provide good standards of living for residents.

What is the role of a global city