It is always nice to have something in the foreground of your photos. The pilings in the Docklands are perfect for this!
Also in the Docklands, are a marina and Webb Bridge, an artistic walking bridge across the Yarra River.
If you tire of walking, trains are going in, out, and around the city at all times. In this image taken from a bridge over the tracks at Flinders Station, some trains are moving fast enough to become mere streaks in my exposure while in others you can see the people.