For those who are not familiar with Parkour and/or Freerunning, this may take a little pre-research to understand. For an example of some training in Adelaide, watch this http://www.youtube.com/watch?v=cV6XNBxItr4 - however there is far more going on behind the movement. Check out www.parkour.asn.au.
A facility designed with Parkour and Freerunning training in mind has many, many positives. It encourages exercise, interaction with public space, it could look artistic in itself, provide entertainment for passers-by, engage youth in healthy and growing activities, the list goes on.
It could be located behind Parliament house, where the 'coloured blocks' are currently fading away (and have suspiciously been left out of any riverbank redevelopment plans). Other locations are also possible.