Spanning the valley of the River Finnan on Scotland’s West Highland Line, the Glenfinnan Viaduct is an engineering marvel. Built between 1897 and 1901 by Robert McAlpine & Sons using pioneering mass‑concrete techniques, the viaduct measures 381 metres long, stands 30 metres high and comprises 21 graceful arches. It carries trains between Fort William and Mallaig, making it the longest concrete railway bridge in Scotland. After its appearance in four Harry Potter films, the bridge gained global fame as the ‘Harry Potter Bridge’, attracting thousands of visitors and prompting safety warnings not to trespass on the active line. Surrounded by loch and mountain scenery, the viaduct offers some of the Highlands’ most photogenic views.