They call Auckland the 'Big Smoke', but in global terms it's hardly a puff really. And that's got everything to do with its geography. The irony of it is that this city of 1.2 million was located on the narrowest part of the country – a slender isthmus just 3km wide at its narrowest point.

You might think that this was something of an oversight by the town planners of the time. What we have ended up with is an urban sprawl to rival some of the major cities of the world. But there's been one very beneficial spin-off – very clean air and a temperate climate. more