Do rent controls and the expropriation of apartment blocks provide an answer to the increasing cost of housing in the rich world? Such radical measures are being considered in many of the world's biggest metropolises, as more and more residents find themselves being priced out of their home cities. Manuela Saragosa speaks to Tom McGath of the Berlin-based campaign group Deutsche Wohnen Enteignen, who wants the city authorities to seize ownership of housing from the German capital's biggest landlords. But leading urbanist Richard Florida of the University of Toronto says there are better ways of tackling the shortage, not least taking on the "not in my back yard" brigade. (Picture: A banner put up by tenants in Berlin protesting against the sale of apartments; John Macdougall/AFP/Getty Images)