Almost 180,000 people move into cities each day...
And now, for the first time in human history, the majority of the world's population live in urban settlements.
Urban settlements can be as large as megacities like Tokyo in Japan, with 35 million inhabitants...
Or as small as the city of Canterbury in the United Kingdom, home to little more than 40,000 residents.
And yet, they have many similarities.
Central Business District
Every urban settlement has a central business district in its historic core.
This trading district is always situated where several main roads meet, and is the primary location for shops, offices, restaurants and entertainment.
High land value means few people live here.
This is the main difference between the central business district and other urban zones.
During the Industrial Revolution, many towns experienced a massive influx of industry workers.
These workers and their families needed accommodation, and so thousands of new houses were built, close together, in a grid-like pattern around factories.
Today, with the decline of many traditional industries, many of these houses and factories have been replaced by wasteland and cheap housing.
With a lack of employment, and low value housing, many inner city areas are characterised by urban decay, unemployment and crime.
Wealthier urban residents can choose a suburban lifestyle on the outskirts of the city.
Suburban houses are often bigger, with gardens, garages and areas of open space.
Beyond suburbia lies the rural-urban fringe – the transition zone between town and countryside – commonly dotted with business parks, shopping centres, hotels and in many cases, airports.
Remarkably, urban settlements follow this basic pattern in almost every town and city in the developed world...
Transcending size, culture and climate.