Terraced Section of the Holyhead Road, with parapet and retaining wall

Cadw's description

Location

The section of the Holyhead Road, now cut off, is near the hamlet of Dinmael, W of Pen-y-bont farm with Pont Glyn Diffwys at the N end.

History

The improvement of the London to Holyhead Road was undertaken by Thomas Telford, engineer, from 1819 to improve communications between London and Dublin. The poor state of the road to Ireland had exercised Parliament from before 1810, and a survey was carried out by Telford in 1811. Monies were granted following the setting up of a commission in 1815, but work on this section could not take place until the amalgamation of the seven existing turnpike trusts, authorised in 1819. The road was not completed until the opening of the Menai Bridge, and the construction of the 20-mile Anglesey section in 1828. Telford designed the road formation, and details of ancilliary structures including tollhouses and milestones, many of which still survive. Sections of the road were severely testing to the engineering abilities of Telford, one being this present section, where the road had to be carried on a cut-and-fill corniche through the gorge, at about 20m above the rapids of the Afon Ceirw. From the second outlook position, in 1854, George Borrow on his tour through Wales, was moved to remark that it was "one of the wildest and most beautiful scenes imaginable". A nearby plinth with a plaque commemorating this was unveiled on 24th July 1996.

Exterior

Section of the old Holyhead Road, approximately 400m long, running along an engineered terrace above the gorge of the Afon Ceirw, above the Pen-y-bont falls. The road formation, recently cut off by a new cutting through the anticline, is 8m wide, with a continuous parapet wall on the outer edge rises directly from the slightly battered retaining wall, generally c5.5m high. The parapet connects with the S parapet of the listed Pont Glyn Diffwys at the N end, and has, from this end at approx. 146m, a narrow looped viewing point or outlook, and, at approximately 373m, a second cylindrical one 'a kind of looking-place...forming a half circle' above the 'profound ravine' (Borrow). The parapet is of stone, rebuilt in certain sections, but originally with stone on edge coping, mostly now replaced with a stone-aggregate concrete coping.

Reason for designation

Included as a representative section of the Holyhead road, one of the first major road engineering schemes in Britain carried out on a national scale since the Roman period, and one where Telford's particular ingenuity was called upon. Also included as a well-known romantic spot, immortalised by George Borrow. Of group value with Pont Glyn-diffwys and the original milestone.