The Ovens River in Bright, Nth East Victoria.
We visited this street in Dunedin, New Zealand on my tour a few years ago. We were told the town planners didn’t visit Dunedin beforehand. They didn’t realise this would result in some very steep streets, including the world’s steepest.
More information about this challenge can be found here http://ceenphotography.com/2014/04/02/cees-which-way-challenge-2014-7/