The UK's housing crisis is acute. We need to build but where? Many critics point to the ample green space which surrounds some of our most overcrowded cities and towns. The green belt celebrates 60 years since it became part of National Policy but its history stretches back far further. The idea of a stretch of land which separates the urban from the rural has been commended as the defining planning policy of the nation. This legislation is at the core of our notion of what it is to live in a 'green and pleasant land'. But is it fit for purpose in the 21st Century? Many critics feel that it is now time to reassess the lines upon which these boundaries were drawn and make a strategic plan for how we want people to live and commute in the near future. The green belt protects many environmental assets closest to our cities but Tom Heap asks whether we are making the most of this vital natural asset.