Glenfinnan Viaduct
The 1,248-foot-long Glenfinnan Viaduct was a genuine wonder when it was built in 1897, and it remains so today. The railway's contractor, Robert MacAlpine (known among locals as "Concrete Bob"), pioneered the use of concrete for bridges when his company built the Mallaig extension, which opened in 1901. In more recent times the viaduct became famous for its appearance in the Harry Potter films. The viaduct can be seen on foot; about ½ mile west of the railway station in Glenfinnan, on the A380 road, is a small parking lot. Take the footpath from here; you'll reach the viaduct in about ½ mile. If you time it right, usually at 11 am, 1:15 pm, 3:15 pm, and 6 pm (confirm times at westcoastrailways.co.uk), you'll see the iconic Jacobite Steam Train crossing the bridge.
