I'm Geoff, 28, originally from France, been in Sydney for 2 years
I did some urbex as a teenager there: supermarkets abandoned for years (super creepy to hang around the offices and the butcher's area!), the abandoned hovertrain prototype track and hangar (http://en.wikipedia.org/wiki/A%C3%A9rotrain), some old factories and cemeteries, a drain, an old cave where the Nazis would repair their planes during WW2 (http://www.cine-resistances.com/98/img/ ... ntagne.jpg), etc.
I didn't even know that urbex existed back then, we just liked exploring with my buddies
Since I moved to Sydney, I did the Middle Head fortifications (with a mate), one abandoned platform at St James (on my own with the help of some dude working there
), the Tank Stream (guided tour). I also went onto some roof at Sydney Uni once to enjoy the view 
Then I found this board yesterday, and now I can't wait to explore more
I'm more into rooftops in the city or around it cos I'm fascinated by skylines, and btw I found a abandoned building in Surry Hills that I haven't had the balls to explore yet by myself, but I know that the rooftop is accessible since I've seen pics taken from the top...
