It is uncertain when the first round towers were built - the first mention of one in Irish sources is an entry in a set of annals c.950AD that refers to the burning of the tower at Slane in Co. Meath. As records of the towers occur quite often in church sources after this date, it seems most likely that the earliest ones date from the ninth or tenth centuries. As many of the towers appear to have been damaged or destroyed by fire, weather or attack, they were often rebuilt, making it hard to date them on architectural grounds.

The tower at Abernethy appears to have been partially rebuilt at some time, as the stone at the base of the tower is very different to that from the top of the doorway upwards. The last reference to a tower being built is in 1238 (Annaghdown, Co. Galway), and it seems likely that these buildings fell out of fashion as Continental influences spread across Ireland, both architecturally and within the church.

The stone towers which can be seen today may not have been the first towers attached to monasteries, for as wooden or wattle churches were replaced by stone ones, there may have been earlier wooden towers, presumably much smaller in stature, which were themselves replaced.  No building of this kind has yet been identified, but wooden constructions often leave little trace of their existence in the archaeological record, and it would be hard to tell the difference between a large hut and a small tower from post-hole marks left in the ground.

The Purpose of the Towers

The exact purpose of round towers is uncertain, but references to some of them in the Irish Annals use the word ‘cloigtheach’, meaning ‘bell tower’.  Rather than functioning in the same way as a modern day belfry, with a bell suspended within the tower, it is thought that a monk would have climbed to the top of the tower to ring a handbell, summoning the other monks to prayer, work or meals.  As well as this practical purpose, it is likely that the towers also had a spiritual one, as pilgrimages and processions within the monastic enclosure were an important part of church ritual at this time.  It is likely that the layout of the monastery and inclusion of certain features such as cross slabs, and perhaps the towers, would have been partly in response to this.

The Design of the Towers

The traditional design of round tower was a free-standing structure, usually between 25 and 30 metres tall and about 5m in diameter at the base, tapering inwards towards the top.  A single doorway, usually raised off the ground, was the only means of access, and there would have been several levels within the tower, with each wooden floor connected to the one below by a ladder.  Access to the door from outside may either have been by a wooden ladder like those inside, or, if the towers were being used in times of attack, a rope ladder, which could quickly be pulled inside.  In many of the towers there were windows at several levels, and four windows, facing N, E, S and W, illuminated the top storey, and presumably helped the sound of the bell to carry across the monastery’s lands.  Most of the towers are thought to have had conical caps, but in many cases these were the first part of the tower to be damaged or destroyed.  It is uncertain if the tower at Abernethy had one of these caps, and none of the antiquarian drawings depict one.

There are no known buildings earlier than the Irish round towers on which their design had obviously been based, and there appears to have been no tradition for the creation of tall buildings in the British Isles before this date (some Roman villas had two storeys but nothing higher than this is known).  Depictions of tall towers can be seen in early European or Byzantine manuscripts, but there is no direct evidence that these were based on real, rather than fantasy buildings.  The most likely source of influence came from the east, as Islamic architectural styles (which included towers or minarets) spread across the Continent.  However, the antiquarian belief that the Irish towers themselves were minarets (or pre-Christian fire temples) can be dismissed.

Further Reading

Lennox Barrow, The Round Towers of Ireland, Dublin 1979

Lennox Barrow, Irish Round Towers, Dublin 1985

Brian Lalor, The Irish Round Tower:  Origins and Architecture Explored, Cork 1999

Roger Stalley, Irish Round Towers, Dublin 2000