Llanfairpwllgwyngyll (long form Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch), also spelt Llanfair Pwllgwyngyll and commonly known as Llanfair PG or Llanfairpwll, is a village and community on the island of Angelesy in Wales, situated on the Menai Strait next to Menai Bridge and across the strait from Bangor.
According to the 2001 census, the population of the community is 3,040, 76% of whom speak Welsh fluently; the highest percentage of speakers is in the 10–14 age group, where 97.1% are able to speak Welsh.
It is the fifth largest settlement on the island by population.
The long form of the name is the longest officially recognised place name in the United Kingdom and one of the longest in the world, being 58 letters in length (51 letters in the Welsh alphabet, where "ch" and "11" count as single letters).
The name is Welsh for "St Mary's church in the hollow of the white hazel near to the rapid whirlpool and the church of St Tysilio of the red cave".