A clas was an institution peculiar to the Celtic church, being a mixture of monastery and college; a place of prayer, teaching, ministry and mission.
Clynnog Fawr rapidly became an important ecclesiastical site, and was also a stopping place for those on pilgrimage to Bardsey Island. Sometimes known as the 'Island of 20,000 Saints', Bardsey was a hugely popular destination for pilgrims in medieval times, with three pilgrimages there being the equivalent of one to Rome.
Clynnog Fawr itself became a place of pilgrimage: the holy well near the church was said to have curative properties, and people spending the night on St Beuno's tomb were said to be healed.
The original church that stood here has long gone, though St Beauno's Chapel, reached along a passageway from the church, is said to stand on the site of the old church and the saint's tomb. This little building has been used as a store and a lock up in the past, and was rescued from ruin in 1913.
The church itself is a handsome building dating from the 15th and 16th centuries. Among the objects of interest inside is a set of dog handling tongs. These are telescopic, with several sharp spikes at the business end. These were used in the days when dogs were permitted in churches and fights and other misdemeanours were common.
St Beuno's Chest is an ancient box, carved out of a single piece of ash wood. This was used to collect offerings from Bardsey pilgrims, and was also where sinners could 'pay' for their sins by putting in a financial contribution.
There is an intriguing 10th century sundial in churchyard, a relic from a time when clocks were unknown, but when the monastic pattern of the day needed to be adhered to.