Some of the earliest Christian stones in Wales are housed inside Penmachno Church. The stones are from the late 5th and 6th Centuries and have Latin inscriptions referring to relatives and hierarchy. Most of the stones were discovered near the church, but one with a rare chi-rho symbol was found near the quarry at the end of the valley. Another feature of interest in the church is the memorial window to William Morgan, the translator of the Bible into Welsh. He was born in the parish at Ty Mawr Wybrnant.