In the south-eastern corner of Llangelynnin churchyard is a well, Ffynnon Gelynin (sometimes known as "The Holy Well of St. Celynin"), a small walled rectangular pool, which was renowned for its power to cure sick children. One old story relates that parents would throw items of their sick child's clothing into the water. If the clothes floated their child would live. If they sank the child was destined to die of the illness.

 

The well was once roofed over but this structure no longer exists. The walls round the well, and probably the benches too, were later additions made when the churchyard was restored. The presence of surface water at this elevation was probably the reason for its designation as a site for early settlement, and the holy well itself almost certainly predates the church.