Travel can narrow the mind. That is to say, contrary to conventional wisdom, going abroad can remind you less of what is different than of what is exactly the same. Having worked internationally on and for cities, I conclude that cities throw up many of the same challenges – and lunacies - wherever we look. We're all in this together.

So despite the fact that Sydney's urban structure and density are profoundly different from a European or indeed an Asian city – though the city is as sprawling as a Phoenix or a Houston – most of the current urban policy issues are the same across the globe, especially with cities experiencing growth.

Sydney faces the choice of whether it wishes to grow up or out. Credit:Chrisopher Pearce

Sydney's population is growing fast. Now at over 1.5 per cent per annum. It will more or less double in size in 40 years or so. And like cities everywhere it faces the choice of whether it wishes to go up or go out. Partly because Sydney doesn't have metropolitan governance – we have 41 councils and no equivalent of Mayor Boris – there is no one to make that choice so in reality we are going both up a bit and out a lot.

Which brings me to 'Shared Global Urban Lesson 1': cities flourish best where they have more metropolitan scale self-government so that such strategic choices and trade-offs can be made. This means not just council amalgamations: it means also devolution of some central (or state) government powers to cities/city regions. This is why Australia is looking at the British "city deals" with such interest as Britain seems to be genuinely embracing empowering its cities. A good start would be for Australia to have an agreed national cities policy.