Visitors can hear the story of the pool with healing waters during an ‘Open Doors’ event in Denbighshire involving scores of historic properties

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For skin conditions, arthritis and rheumatism, a dip in its chilly waters is said to work wonders. But to fully benefit from the mystical North Wales pool’s restorative powers, if only spiritually, one man decided further measures were needed.

Dyfnog cast off his wealth, became a monk and stood in the cold waters of a waterfall that fed the pool in a damp Denbighshire wood. For long periods he stayed there wearing nothing but a shirt of thick horse hair fastened with an iron belt. Living on bread and water, he saw it as a form of penance that allowed him to atone for his sins.

It’s not known how his health fared, but he was apparently fit enough to build a small wooden church nearby. Arthritis may have caught up with Dyfnog eventually, but so did fame: more than 1,000 years later, hordes of people began descending on the same sacred pool of water, desperate for miracle cures.

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For his pains, Dyfnog was later canonized. His plunge pool – fed by a spring – became known as Ffynnon Dyfnog (Dyfnog’s Well). As word spread of its healing powers, the original 6th century church was replaced by a 13th century stone construction. The village of Llanrhaeadr sprang up, taking its name from the same hillside spring – Llan meaning “church” and rhaeadr “waterfall”.

A further 300 years on and everyone knew about St Dyfnog. A building was erected over his well and changing rooms were added to enable visitors to dress appropriately for their plunge. Other buildings included a chapel bearing images of the 12 Apostles. Three bridges were constructed to improve site access and amenity.

For St Dyfnog’s Church, penance became big business, with shivering bathers paying for their piety in the form of a donation. The pool became a sunken bath, lined with cut stone and reputed to have been clad with marble.

By the early 16th century, the holy well had become one of the most visited in North Wales, in the big league alongside the likes of St Winifred’s in Holywell, Flintshire. Money poured in, enabling St Dyfnog’s Church to install the elaborate 16th century Tree of Jesse window, a depiction of the ancestors of Jesus Christ.

Almost 600 years later, the stained glass window remains the church’s crowning glory. In fact, it was lucky to have survived much more than a century: to save it from destruction by Oliver Cromwell’s men, it was removed and buried nearby.

Fashions change, science progresses, and from the late 18th century people stopped visiting St Dyfnog’s Well. Perhaps they’d just realised expensive piety and bone-numbing dips weren’t actually banishing their aches and pains.

But maybe Dyfnog was right all along: cold-water therapy is now thought to reduce inflammation, boost immune systems and release "happy hormones". It is also said to be good for the skin, just as those 16th century pilgrims insisted it was.

With so many quack cures being promoted on social media, are we much better off now? Share your thoughts in the comments below.

By 1808, the bathhouse had collapsed, and by 1880 little remained of the site’s former buildings. But the well was never entirely forgotten. Even now it remains a popular place for pilgrims, and occasional baptisms are held there.

For the past decade, volunteers at Llanrhaeadr YC Preservation Society have been restoring the pool, now Grade II-listed. With Heritage Lottery funding they have repaired the three 16th century bridges and built a path to allow better access to the site.

St Dyfnog’s church and its well will feature in this year’s Denbigh Open Doors event between September 23-25. It’s one of 15 local churches that will be welcoming visitors over the three days, along with many of the Denbigh area’s 200 listed buildings.

Elfed Williams, chair of Llanrhaeadr YC Preservation Society, is delighted with the results of its work at St Dyfnog’s well. “It was a real labour of love,” he said. “The tales of the waters’ healing powers gives the place a real sense of tranquillity, and we look forward to sharing the story with visitors.”

Another highlight of this year’s Denbigh Open Doors is the chance to visit Denbigh Library, originally the town’s county and shire hall. It is celebrating its 450th birthday, having been constructed in 1572, the same year that Humphrey Llwyd’s first map of Wales was published.

Originally, the building’s ground floor was a colonnaded covered market space, with council and courtrooms above. During the Victorian era, police cells were added for prisoners waiting to enter the courts. Later, the county council later convened at the building.

A notable feature of the building is the town’s clock. In 1858, gas lighting was introduced to power the device, not entirely successfully. Contemporary newspaper reports describe puzzled residents arriving too early for appointments, church services and train journeys. It was said to be eight minutes ahead of Greenwich Mean Time.

In 1989 the building became the town’s library. Four years ago it was refurbished and library manager Meira Jones will be showing visitors its facilities. “We look forward to welcoming visitors to a guided tour of the building as we mark its very special birthday,” she said.

As Denbigh Library is the central information point for the Open Doors event, people can pre-book tours and other activities there (01745 816313). Menter Iaith Sir Ddinbych will also be offering Lego and Minecraft workshops for youngsters at the library. Welsh and bilingual sessions are available on Saturday, September 24 (booking essential via 01745 812822 or menter@misirddinbych.cymru).

One part-renovated building opening its doors to the public is also one of the oldest on Denbigh’s high street. A work in progress, The Forum will soon accommodate a holiday let, three business spaces and a cafe. The open doors weekend will give people a sneak preview of the long-awaited project.

Chris Evans, chair of Denbigh Open Doors, said he was “super excited” by the 2022 event. “Denbigh town’s 4.7ha of walls gives people a real insight of the town from differing angles,” he said. “And outside the town there are a number of stunning locations for people to see.”