12. Crossing continents

If you live in Britain – and if you don't, I sort of envy you right now - you'll know that it's a pretty torrid time in politics right now. Next Thursday, there's a referendum to determine whether the UK should remain a member of the European Union. So, since migration to cities is this week's theme – and since it's, frankly, about all we can think about right now – Barbara and I begin this week's episode by talking about that referendum, and why cities so often have a more international outlook than their hinterlands. This week, you can also hear: Emmanuel Akinwotu on how Lagos has coped with ballooning from a city of 1m, to one of 20m, in under half a century; Olivia Cuthbert on her experiences visiting Za'atari, the refugee camp that's rapidly solidifying into Jordan's fourth largest city (this week's header pic was taken inside that camp); Lyman Stone, an agricultural economist for the US government, on life in the city Americans love to hate, Washington DC; And finally, our map of the week – which, I'll be honest, we do no justice to whatsoever - is a magnificent piece of work by Duncan Smith of UCL's Centre for Advanced spatial Analysis. It shows, at a glance, the growth of all the world's major cities over the past 60 years.