Plodded off to Sydney for another history talk this morning. Didn't get much sleep last night so I wasn't at my alertest ever. But it was an interesting enough talk. Poked around the Quay after having another look for the Tank Stream but still no luck.
(Big version. The Tank Stream goes from the middle to the left. And Sydney Cove is now Circular Quay.)
Got some maps. Including the one above. In it Sydney looks pretty much as it does now. The Tank Stream's still there underground. It's been in a pipe for a long time and somewhere there's a glass floor where you can see down into a hole in the pipe and have a gander at it.