Bardsey Abbey

The ruins of the Abbey of St Mary, stand at the northern end of Bardsey Island, south-west of the Lleyn Peninsula, in Gwynedd, Wales. The site has had religious importance from at least the 6th century when Saint Cadfan founded an abbey there. In the following centuries the island became an important place of pilgrimage and 20,000 saints are reputedly buried on the island. By the end of the Middle Ages the abbey had declined in importance and, following the dissolution of the monasteries, fell into ruin. In the 18th century, more substantial remains were still standing, but by the 20th only the current remnant of a tower remained. The ruins are a Grade II* listed building and a scheduled monument. Three Celtic crosses set among the ruins are listed at Grade II.

Monastery data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).