According to tradition, this monastery was founded by none other than St. Patrick himself, and its prime location on land sloping towards Lough Foyle to the east would have made it an ideal spot for an early Christian settlement. The site consists of churches, a graveyard, and the remains of what was once a larger ecclesiastical enclosure, all of which point to its significance as a religious centre in medieval Ireland.

In 2014, the Bernician Studies Group conducted a magnetometer survey of the fields surrounding the site, revealing the outline of the original ecclesiastical enclosure that once defined the boundaries of this Early Christian monastery. This geophysical investigation provided valuable insights into the extent and layout of the monastic settlement that would otherwise remain hidden beneath the ground. The survey work complemented earlier historical research that had identified Cooly as an important religious site dating back to the early medieval period.

During a clean-up scheme in 2010, several previously unrecorded cross-slabs came to light within the graveyard, adding to our understanding of the site’s stone carving tradition. Among the discoveries, the Bernician Studies Group documented a particularly intriguing find: a freestanding, rough L-shaped slab standing about 20 centimetres high. This piece appears to be an unfinished ringed-cross slab, possibly abandoned by its stonemason before completion. Its similarity to another nearby slab suggests there may have been a workshop or tradition of stone carving at Cooly, where craftsmen created these important symbols of Christian faith and commemoration.