Why has urban housing become so unaffordable around the world? Are rich international investors from China and elsewhere to blame? Manuela Saragosa speaks to architect James Law about the horror of "cage" living in his native Hong Kong, the world's least affordable city, and how his Cybertecture firm hopes to solve the problem with "Opods" built out of mains water pipe sections. Meanwhile, Phil Mercer reports from New Zealand on new legislation aimed at stopping foreign property buyers driving up property prices there. But London home buying agent Henry Pryor argues that laws like these may be misguided, as they do not target the true cause of spiralling house prices. (Picture: 78-year-old sits in his cage dwelling in Hong Kong; Credit: Daniel Berehulak/Getty Images)