The railway from Mallaig to Fort William is the most beautiful one I think, and the scenery outside the window makes you feel like you are in a movie. And the Glenfinnan elevated is definitely the most representative stop, needless to say, because of Harry Potter. It is recommended to get off here, walk a circle along the hiking path through the viaduct, and step on the mountaintop of the highland to feel the wind. Of course, a photo with the elevated is indispensable.