Major cities such as Sydney have been building underground for over 100 years and developing new underground infrastructure is impacted on by what already exists. Until now there has been no easy way of finding out exactly what is down there. To overcome this, the NSW Government Department of Lands Sydney Down Under project is collecting as much data associated with Sydney's existing underground infrastructure as it can locate, with the aim of revisualising it in 3D format for a more accurate picture of what lies underneath Sydney, and to store it all in one central database for future use by planners of new underground developments. For the full report go to: Going underground, Radio National Future Tense, broadcast Sunday 4 November 2012.