Keady has an unusual place in Irish railway history, being noteworthy under two headings.
The first is that as a station on the cross border line from Castleblayney to Armagh (a line that is also noteworthy as the last commercially funded standard gauge line to open in Ireland before the decline set in), the station became a terminus in 1923 after the cross border element of the line was closed, leaving Keady as a dead end terminus in south Armagh. The town also has a railway viaduct, albeit south of the station and therefore not in active use post 1923. The more interesting fact about Keady is the presence of a never used railway "tunnel".
Describing the infrastructure in question as a tunnel is technically incorrect - what was actually built were two underbridges to carry the line from Castleblayney to Armagh over the route of the never built Ulster & Connaught Light Railway. The latter was a madcap scheme to build a narrow gauge railway from Greenore, Co. Louth, to Clifden Co. Galway, via Newry, Bessbrook, Keady, Tynan, Maguiresbridge, Bawnboy Road, Dromod, Rooskey, Tuam and Cong to Clifden. As this line was authorised around the same time as the line from Castleblayney to Armagh, the builders of the latter had to accommodate the proposal with a bridge under their line at Keady. As the U&CLR never came into existence, the tunnel has never had a train run through it.
The tunnel remains to this day, in use as a bus garage for a single bus.