The O’Shannassy Aqueduct was completed in 1914 to carry water from the O’Shannassy River to the Surrey Hills reservoir, 70 kilometres downstream. The genius of the design is that the water moves entirely by gravity — the channel falls by only a few centimetres per kilometre, hugging the contour line around the slopes of Mt Donna Buang and threading across smaller creeks on a series of stone-and-concrete bridges.
The aqueduct was decommissioned in the 1990s and the service track that ran alongside it is now an off-road walking and cycling trail. It’s one of the gentlest gradients in the upper valley — a long, level traverse high above the township, threading in and out of cool gullies and pulling out into clearings with views straight back to Melbourne on a clear day.
Pick up the trail at any of several access points along the Acheron Way; an out-and-back walk of a few hours is plenty.