Conservation of the built environment refers to the conservation of any monument, building or site that has historical significance. Urban conservation means the sensitive use and adaptation of an urban area or part thereof, so as to maximise its desirable historic, aesthetic or social attributes and to enhance the value of the area, both for its present users, and for the future (NMC, 1994). In South Africa a historical site is defined in the National Monuments Act of 1969, as "any identifiable building or part thereof, marker, milestone, gravestone, landmark or tell older than 50 years" (NMC, 1997c). The historical heritage of Greater Johannesburg consists of those buildings, works, places and objects, which are associated with events that have occurred throughout the history of the city. This heritage is a valuable, finite, non-renewable and irreplaceable resource, which must be carefully managed to ensure its survival.