Gallen priory (church) sits on the original site of a monastery that was established in 492. A group of Welsh monks restored the community after its buildings were burned in 820. They operated a school at this location for many years afterward.
Today, there is a church from the 13th century located there, along with a group of rare cross slabs from the early Christian period. The slabs probably date back to the 8th to 11th century. Quite a few of then have been used in the rebuilding of the church, attached to the gables.
One of the slabs is inscribed with the words OR DO BRALIN. The slab located at the centre of the church is intricately carved with deer, fretwork and interlacing. Another features a ringed cross with a solitary figure standing beneath it.