Road tunnel carrying the A55 North Wales Expressway (nprn 403728) through Penmaen-bach headland. The tunnel, some 170 metres long, was opened in 1932 and now carries only eastbound traffic; westbound traffic uses the 1989 tunnel (nprn 403560) to the south, although provision has been made for a new eastbound tunnel parallel to it. Around the headland itself, known as the Giant's Thumb, the route of Thomas Telford's early nineteenth century road can be followed; this was the A55 before the tunnel was constructed.
B.A.Malaws, RCAHMW, 17 February 2014.