Old Church ruins, Duncrun Road, Tamlaght, Bellarena, Limavady, Co Londonderry

The ruins of the old church at Tamlaght stand on a knoll overlooking the plain of Magilligan, nestled beneath the woods on the slopes of Binevenagh. They measure 20 metres by 6 metres externally and are correctly oriented with the long axis running west to east, following the traditional ecclesiastical plan with entrance door in the west wall and altar in the east.

The building is constructed in random rubble basalt with occasional other stone. The east and west walls retain their original gabled form. The south wall survives to approximately 1.5 metres high, while the north wall stands roughly to the height of the former wall-plate level. The west wall contains a rough stone arched opening assumed to be the original west door. The east wall features a tall, narrow pointed window trimmed with much-eroded red sandstone, with deep recessed and splayed reveals also trimmed in sandstone. A stone relieving arch appears internally above this window. This window would have been impressive in its original state.

At the east gable is a grave reputed to be that of Saint Aidan, marked by a hand hole in one side. Along the south wall are additional openings, including a partially built-up opening towards the west end with what appears to be a segmental stone arch. On the north wall is an opening without arch or head, and a blocked-up narrow opening in concrete block that may have been a doorway. The stonework shows evidence of former plasterwork internally. On the south wall internally, at 1.5 metres high towards the west end, is an incised sketch on weathered red sandstone depicting a mitred bishop on horseback.

The history of the site is complex and partly legendary. According to historical sources, a church near this location was said to have been founded by Saint Patrick in Tamlaght. There is some confusion in the records between different saints associated with the church: Saint Cadan, reputed a disciple of Patrick; Saint Aidan, first bishop of Lindisfarne, whose bones are said to have been brought to this church after being taken from Iona when the Columban Federation left that monastery; and Saint Gedeni, also quoted as patron. The existence of the grave and a nearby well suggests the site may be of very early Christian date, though whether these ruins represent an early Christian edifice or a later medieval building remains uncertain.

The documented building history shows that at the Plantation in 1622 the church was "re-edified" by Will Gage, the bishop's tenant. In 1693 the church was recorded in good repair, though it likely suffered damage during the 1641 rebellion and possibly later in the century. By 1768 it remained in "pretty good repair". However, in 1784 a new parish church was built in Duncrun near the ancient monastic site, and the abandoned church building was given by the Earl of Bristol, bishop, to Catholics for use as a chapel. This Catholic use was subsequently abandoned when a new church was built adjoining the site in 1826.

The ruins conceal the location of the present Church of Saint Aidan's and remain important for their historical relevance to the area and their association with stories of the Columban Federation, as well as their connection to both the present Church of Ireland and Roman Catholic churches in the parish.