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Cof Cymru: National Historic Assets of Wales · Wales

Britannia Bridge

Porthmadog, Gwynedd, Wales

The record

Designation
Listed building, Grade II
Broad class
No class recorded
Date of designation
26 September 2005
Locality
Porthmadog
Town
Porthmadog
Community
Porthmadog
Unitary authority
Gwynedd
Country
Wales
Coordinates
52.92471, -4.12748
Cadw reference
85367

Slide toward Today to fade the historical sheet and see the modern map underneath.

David Rumsey Map Collection, Stanford Libraries

Shown on 5 historical map sheets, the earliest the 1795 "To Sir Watkin Williams-Wynn Bart ... the map of the six counties of North Wales is most humbly inscribed by his obedient humble servant" (Llyfrgell Genedlaethol Cymru – The National Library of Wales).

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This record in Cadw's own full report ↗

Cadw's description

At the N end of the harbour and standing between the town centre and the Cob.

Built 1808-11 contemporary with the Great Embankment (The Cob), William Madocks' grand scheme to reclaim Traeth Mawr for agricultural land, and to carry a road on Madocks' proposed London-Dublin postal route. Construction was probably supervised by John Williams, agent to Madocks. The bridge acted as a tidal sluice, and retains its slots for tidal gates.

A double-carriageway 5-bay bridge, of large blocks of squared local stone laid in regular courses. The original construction is best observed on the N (landward) side. Segmental arches have freestone voussoirs, and keystones recessed. Prominent rounded cutwaters retain slots for tidal gates, and above them are shallow buttresses carried up to a raised band at the base of the parapet. The parapet spanning the river is C20, of coursed slate-stone. Above the abutments the original parapet has survived, which is lower, and curves out to round terminal piers, which on the E side abuts Bridge Cottage. On the S (harbour) side the bridge has been extended by widening of the deck to accommodate a footway, which is supported on the cutwaters. These cutwaters also retain slots for tidal gates. The C20 parapet is similar to the parapet on the N side.

Listed, notwithstanding later widening, as an integral component of William Madocks' grand reclamation scheme, as represented by the Cob, and for its contribution to the historical integrity of the harbour. The bridge retains important evidence for its original design and construction.

Nearby in the register

Other entries of the same register within about three miles of this one, by straight line.

Designated Historic Asset GIS Data, The Welsh Historic Environment Service (Cadw), 2026-09-07, licensed under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Cadw, the Welsh Historic Environment Service · Open Government Licence v3.0
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