The Franciscan friary at Llan-faes was founded in 1237 by Llywelyn ab Iorwerth (Llywelyn Fawr or Llywelyn the Great) as a memorial to his wife Siwan, daughter of King John, who was buried there.
The placename 'Llan-faes' is believed to derive from the Welsh word 'mes', meaning 'acorns' [Llan+mes/Llan-faes]. It is notable that acorn and oak-leaf motifs appear on many of the tiles found at Llan-faes Friary.