Description: The bridge spans the Mynach, a tributary of the Rheidol. The bridge is unusual in that three separate bridges are coexistent, each one built upon the previous bridge. The most recently built is an iron bridge  (1901), which was built over a stone bridge (1753), which was built when the original bridge was thought to be unstable. The builders of the 1753 bridge used the original bridge (built 1075–1200) to support scaffolding during construction.

The bridge is at a point where the River Mynach drops three hundred feet in five steps down a steep and narrow ravine before it meets the River Rheidol.  

According to the legend the original bridge was built by the Devil, as it was too difficult for mortals to build. The agreement stipulated that the Devil would build the bridge in return for the soul of the first living thing to cross the bridge. The Devil built the bridge but was tricked by an old woman who threw bread onto the bridge. Her dog crossed the bridge for the bread, thus becoming the first life to cross the new bridge.

Devil's Bridge has been a tourist attraction for centuries. The celebrated English author George Borrow wrote Wild Wales (1854), which includes a lively, humorous account of his visit to Pontarfynach.