Glenfinnan viaduct tours: the 21 arches, the steam train and the timing

The West Highland Line was pushed through to Mallaig at the end of the nineteenth century, and the Finnan valley was the problem. It was too wide to bridge cheaply in stone and too remote to carry stone to.

Robert McAlpine solved it with mass concrete — poured, not cut — at a time when the material was distrusted for anything that had to carry a train. He used it so consistently across his career that he was known as Concrete Bob, and the Glenfinnan viaduct is still the longest concrete railway viaduct in Scotland.

The numbers are worth having in your head when you stand under it: twenty-one arches of fifteen metres each, thirty metres above the river, three hundred and eighty metres end to end, and every metre of it on a curve. The curve is what makes the photographs work — you can see the train and the arches at the same time, which you cannot do on a straight bridge.

It opened on 1 April 1901 and has carried trains ever since. There is no fence, no ticket office and no entry fee. There is a footpath from the visitor centre car park up to the viewpoint on the hillside, which takes about fifteen minutes at a walk and is the shot everybody comes for.

The Jacobite is a working steam service between Fort William and Mallaig, and it crosses the viaduct twice a day in season. It has been in a well-known series of films, which is why the viaduct is now one of the most visited spots in the Highlands.

The 2026 season runs from 1 June to 23 October for the morning service, with an afternoon service added from mid June to late September. Westbound, the train leaves Fort William around 10:15 and crosses the viaduct at roughly 10:45 to 11:00.

Tours that advertise the train build their morning around that window, which is why the good ones leave Edinburgh at half past seven rather than eight. If your listing does not mention the train at all, assume you are arriving after it.

Two honest notes. First, the crossing takes about ninety seconds — it is a wonderful ninety seconds, and it is ninety seconds. Second, in high summer the viewpoint has several hundred people on it by half past ten. Neither of those is a reason not to go; both are reasons to know what you are booking.

Outside the season the viaduct is empty, the light in October is better than in July, and ordinary ScotRail trains cross it several times a day. They are not steam, but they are trains on a curved viaduct in the Highlands, and most people photograph them anyway.