Knapsack Gully Bridge — where sandstone arches meet mountain mist 🌿🪨 Wandering through time at Knapsack Gully Bridge — a breathtaking sandstone viaduct nestled in the Blue Mountains. Built between 1863 and 1865 as part of the pioneering Lapstone Zig Zag Railway, this seven-arched marvel was once hailed as the finest piece of masonry in New South Wales. Designed by John Whitton, the bridge carried steam trains up the mountains and later served as a roadway before becoming the scenic walking tra