A public footpath and a bridleway at its southern end provide access from the A470 road and from Cefn-coed-y-cymmer.
It is the third largest viaduct in Wales and was designed by engineers Alexander Sutherland and Henry Conybeare.
Cymer, Inc. a company making light sources for semiconductor fabrication
Gwerclas usually refers to a former castle and farmstead close to Cymmer in the parish of Llangar in the ancient cantref of Edeyrnion, Wales.
It is from the youngest of these sons, Iorwerth ab Owain ap Madog ap Maredudd, that the barons of Cymmer yn Edeyrnion claim descent.