To what extend is the traditional model of imprisonment still relevant today? Has the time come for a radical re-thinking of the notion of punishment? Is restorative justice the notion that will 'penetrate' the prisons' walls and manage to alter and re-shape the concept of imprisonment? Restorative justice advocates have been sceptical about the compatibility and appropriateness of implementing restorative programmes in prison regimes. Although such programmes, being largely at an experimental phase, have already been developed within custodial settings, critics still tend to be conflicted about the possibility of integrating a restorative justice ethos within a punishment-based institution, such as prison. These criticisms, raised in the present article, are based on existing conceptual and operational obstacles concerning the very nature of prisons, which are taken into consideration before envisaging or providing guidelines for the construction of a 'restorative prison'.