Pont Aberglaslyn has a bridge with a connection to the Devil. It is very similar to other Devil and bridge related stories found throughout the British Isles. The Devil built the bridge on the understanding that he would receive the soul of the first living creature to cross over it. When the bridge was finished he went to the local inn to inform the magician Robin Ddu that it was ready. Robin went to inspect the new bridge with a dog he lured from the pub with a fresh baked loaf of bread. Upon seeing the bridge Robin asked the Devil whether it was sturdy and how much weight it could carry as he thought it might not even take the weight of the loaf he was carrying. The Devil was shocked and demanded that the magician throw his loaf onto the bridge to prove that it was indeed strong enough. So Robin threw the loaf onto the bread and the dog chased it across the bridge, thus cheating the Devil of a human soul. Robin Ddu then returned to the pub to finish his drinking.
Robin Ddu or Black Robin the Magician, or more correctly Robin Ddu ap Siencyn Bledrydd of Anglesey, lived circa 1450. He was a poet and sometimes a known as a prophetic poet, and about ninety of his pieces are still preserved on manuscripts. It would appear that Robin also pretended to be a sorcerer or wizard
and he appears in many Welsh tales.