The state of affordable housing in major cities around the world is an issue of increasing concern to politicians - and of course to the growing population of large cities. Next month, the UN's World Urban Forum will discuss rapid urbanisation and the pressures it brings on cities’ infrastructure and housing. In Germany, Berlin is the first city in German history to impose rent controls. In London, an inquiry into the disastrous fire in an inner city high rise block has highlighted the quality and safety concerns surrounding affordable accommodation in the capital. Everywhere urban planners are asking: can large cities provide affordable quality accommodation for residents? Paul Henley and a panel of expert guests discuss the big challenges facing local authorities and city dwellers around the world.