The concept of the neighbourhood unit, crystallised from the prevailing social and intellectual attitudes of the early 1900s by Clarence Perry, is an early diagrammatic planning model for residential development in metropolitan areas. It was designed by Perry to act as a framework for urban planners attempting to design functional, self-contained and desirable neighbourhoods in the early 20th century in industrialising cities. It continues to be utilised (albeit in progressive and adapted ways, see New Urbanism), as a means of ordering and organising new residential communities in a way which satisfies contemporary "social, administrative and service requirements for satisfactory urban existence".