Railway Tunnel, Killiecrankie

Killiecrankie Viaduct is a railway viaduct designed by civil engineer Joseph Mitchell in 1863. It features a curving structure with 10 segmental arches made from roughly coursed, squared, and snecked bull-faced rubble. The arches are accented with raised ashlar voussoirs, brick infill, and brick-lined arches. Notable architectural elements include a corbel course, a saddleback-coped parapet, and crenellated turrets with gunloops.

On the southwest elevation, a turret projects from the center pier, flanked by five regular arches, each supported by three cast-iron tie-plates. Additional turrets are located on the outer piers, with the turret on the right featuring a small carved head. These elements are connected by a continuous corbel course and parapet. To the right, a contrasting darker rubble approach wall leads to a two-stage turret with a reduced upper stage and a narrow floodwater arch. A parapet wall on higher ground to the left leads to the tunnelmouth.

The southeast elevation of the tunnelmouth is approached by stepped walls that lead to a moulded tunnelmouth, which is characterized by large square voussoirs. This section transitions into a corbel course and parapet that includes a raised moulded tablet and flanking corbelled turrets.