New evidence, brought to light by researchers from Queen’s University Belfast (QUB) and local historians from the Derry Tower Heritage Group, suggests that a ‘lost’ medieval round tower may in fact have been hiding in plain sight in the heart of Derry City for centuries.
Located on the grounds of the Lumen Christi College grammar school, the monument was previously thought to be the ruins of a 17th-century windmill. But, thanks to the efforts of the Derry Tower Heritage Group and their foresight in collecting mortar samples from the building when it underwent conservation work in 2013, the tower has now been directly dated to between the 13th and 14th centuries AD. This was achieved using an innovative new technique for radiocarbon dating building-mortar, which is currently being refined at the 14CHRONO Centre for Climate, the Environment, and Chronology at QUB. This method measures the amount of 14C that was effectively ‘trapped’ in the mortar when the lime originally set.
Dr Gerard Barrett, Research Fellow from the School of Natural and Built Environment at QUB, carried out the analysis on the tower’s mortar. He explained, ‘The radiocarbon dates we obtained indicated that the fabric of the round tower was from the medieval period. The work that local historians in the Derry Tower Heritage Group had previously carried out suggests that a medieval round tower existed in this general location in 1600.
‘By 1685, however, the round tower is no longer shown on any historic maps, but a windmill is shown on the outskirts of the city,’ he continued. ‘The radiocarbon dates are not saying that the tower was not reused as a windmill in the 17th century, but it would seem that the 17th-century builders were making-do and mending, using the stump of the old round tower for a new purpose.’
It is likely that the tower represents the remains of the cloigtheach (or bell house) of St Columba’s monastery, which is known to have been located in the vicinity of the monument during the medieval period. Medieval round towers of this kind are found almost exclusively in Ireland, with around 90 known examples. While their main practical function was as a bell tower, they were also a symbol of status and power for a monastic community.
Speaking about the significance of the discovery for the city, Dr Colm Donnelly, Director of the Centre for Archaeological Fieldwork at Queen’s University Belfast, noted, ‘This monument is the only medieval structure still standing in Derry. All other medieval buildings that were once here are now gone, buried under the centuries of building activity that have happened in the city over the past 400 years.’
With this discovery it is hoped that excavations will soon be carried out in the surrounding area to learn more about the St Columba monastery, of which little is currently known.
This review appeared in CA 345.