The Old Church of St Nidan, Llanidan, was in use until the middle of the 19th century when it was replaced by St Nidan's Church, Llanidan, nearer to the village of Brynsiencyn. This was for two reasons: the old church needed repair, and also because the population of Brynsiencyn needed a church. The old church was then partially demolished. The new church contains a sandstone reliquary, about long, which is said to contain Nidan's relics. The reliquary's date is uncertain: it has been described as being "probably" from the 14th century, but also, in a more recent description, as "probably 16th century". It was found buried under the altar of the old church in 1700.
