I discovered this beautiful mysterious old structure at the top of a hill near Bondi Junction, Australia.
Now that I'm back home in Israel I have time to research what it was that I saw.
Turns out that this is Waverley Reservoir (Elevated) (WS 136) and its story is here.
The water supply reservoir was built a century ago, completed in 1917.
I hope the heritage people will take good care of it.
(Linking to Watery Songlines meme in Australia.)