Robert McAlpine built the Glenfinnan Viaduct for the Mallaig extension of the West Highland Line at the end of the 1890s, and it opened in 1901. Made entirely of mass concrete — then a bold new material — it carries the railway on 21 arches in a graceful curve round the head of the glen, up to 30 metres above the valley floor.
Films had found it long before Harry Potter (Ring of Bright Water was shot here in 1969), but since Chamber of Secrets it has been the bridge the Hogwarts Express crosses. A path from the visitor centre car park climbs to a viewpoint above it, and a longer walk takes you under and behind the arches. To see a train cross, check the Jacobite steam train times at the visitor centre — and expect company.