Pont-y-cafnau is the world’s oldest surviving iron railway bridge and cast iron aqueduct. It is one of the most treasured industrial heritage sites in the UK and a monument of Merthyr Tydfil’s historic iron production. The bridge is currently closed and awaiting restoration.
|County||Merthyr Tyfdil County Borough|
|Maintained by||Merthyr Tydfil County Borough Council|
|Designation||Scheduled Ancient Monument|
|Listed status||Grade II*|
What is the best way to enjoy Pont-y-Cafnau?
Currently, you can only approach Pont-y-Cafnau from the southern entrance. There is an information board to your left.
A close inspection of the bridge deck gives you a view of the original chairs and seating for the Gurnos Tramroad, which delivered limestone to Cyfarthfa Ironworks nearby.
The surviving water trough underneath the bridge decking is visible from a side vantage. The water was delivered to the ironworks from Cyfarthfa Leat, which runs from the Taf Fechan. This vantage also gives you a good view of the supporting cast iron A-frame trusses, evidence of Watkin George’s previous training as a carpenter. Such trusses were commonly made from wood and used to support a roof.
To the side of the bridge on the right is the remains of the water turbine house that once powered Merthyr’s electric trams, then generating hydroelectricity for the town.
You cannot walk across the bridge at the moment due to safety reasons and the northern entrance is fenced off; therefore, you may wish to extend your visit by visiting other nearby attractions such as the remains of Cyfarthfa Ironworks and Cefn-coed Viaduct.
How long does it take to see Pont-y-Cafnau?
It will take you around 5 minutes to see the bridge with its current restrictions, so plan to include this attraction as part of a visit to other sites of interest in the local area.
Is Pont-y-Cafnau suitable for a picnic?
There are green areas near the bridge around the site of the Cyfartha Ironworks and Taff Valley, which are suitable for a picnic.
How do I get to Pont-y-Cafnau?
If you are arriving by car, you may wish to choose to park in Cyfarthfa Retail Park North, bear in mind there are parking restrictions so please read them carefully before deciding. There is a path behind B&Q that leads you down to the bridge.
Pont-y-Cafnau is a 1.5 mile walk from Merthyr Tydfil Railway Station, which will take you roughly 30 minutes. There are also many bus stops nearby with services to and from Merthyr.
History of Pont-y-Cafnau
1765 – Cyfarthfa Ironworks is established by Anthony Bacon.
1767 – The first blast furnace constructed.
1792 – A 4 ft guage tramroad from the Gurnos limestone quarries to the ironworks was completed.
1793 – Pont-y-Cafnau is constructed, to replace a timber predecessor. It was most likely designed by Watkin George, the engineer of Cyfarthfa Ironworks. It carried the Gurnos tramroad over the River Taff, just south of the Taff Fechan and Taff Fawr confluence. The bridge also functions as an aqueduct carrying water from the Taff Fechan via a trough under the bridge deck .
1796 – George constructs the Gwynne Aqueduct. Constructed from wood, it carried a trough on trestles through the air, delivering water to power a great wheel named ‘Aeolus’, which powered a blowing engine for the furnaces. The bridge held wooden panels, which supported inverted trusses that carried the trough as demonstrated in this 3D impression.
The wheel was discontinued and replaced with a steam powered successor in the early nineteenth century , which could explain why there is no trace of the Gwynne Aqueduct today.
1921 – Cyfarthfa Ironworks is abandoned after a brief wartime flourish. The site had effectively closed 11 years earlier .
1928 – The water rights of the ironworks leats were purchased by the Merthyr Electric Traction & Lighting Company. A water turbine house was constructed next to Pont-y-Cafnau.
1929 – Slight adjustments to former water supply of the ironworks directed supplies for the to the new turbine house, where electricity was generated for Merthyr’s electric trams.
1939 – Merthyr’s electric trams cease. Electricity generation at Pont-y-Cafnau continues.
1953 – Electricity generation ceases .
1975 – Pont-y-Cafnau is first designated as a listed structure .
2020 – Pont-y-Cafnau is included in a major plan approved by Merthy Tydfil Council to transform Cyfarthfa Castle and Park and the surrounding area turned into a major museum and visitor attraction based on the town’s world-renowned industrial heritage.
2021 – We visited the bridge and found it closed to the public, which would suggest it is awaiting restoration.
- Cadw (2015) Merthyr Tydfil: Understanding Urban Character. Cardiff: Cadw.
- Visit Merthyr (2020) Pont-Y-Cafnau Bridge. Available at: https://www.visitmerthyr.co.uk/things-to-do/places-of-interest/pont-y-cafnau-bridge/ (Accessed 24 April 2022).
- Cadw (2020) Pont-y-Cafnau. Available at: https://cadwpublic-api.azurewebsites.net/reports/listedbuilding/FullReport?lang=&id=11408 (Accessed 24 April 2022).
- Lewis, A. (2020) ‘New 20-year plan to create new tourist attraction celebrating Merthyr’s industrial heritage’, Wales Online. Available at: https://www.walesonline.co.uk/news/local-news/new-20-year-plan-create-19233385 (Accessed 24 April 2022).