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An Investigation into the Origin and Purpose of Ireland’s Round Towers, 2024

A depiction of the Clondalkin Round Tower, London Illustrated News 1844. This tower is so sturdy that it did not budge when a gunpowder factory nearby exploded in the late 18th century.

There are 67 confirmed round towers in Ireland, where at least a part survives, as well as 23 sites that are generally accepted to have ‘once’ been home to a round tower. As well as these 90 towers, another 38 sites were considered as potential towers but classified as ‘doubtful’ in George Barrow’s survey 1970-1978.[1]

For almost 200 years, the accepted story of these round towers is that they were (a) bell towers, (b) places of refuge from Viking warriors, (c) treasure stores for monastic riches and (d) beacons, from which messages could be transmitted to the neighbourhood.


Petrie’s Gospel


Most of the above theories arise from a work written by George Petrie (1790-1866), a Dublin-born son of a Scottish portrait painter who became one of Ireland’s leading antiquarians. In 1831, Petrie successfully persuaded the Royal Irish Academy, of which he was a member, to offer the Cunningham Medal to whoever came up with the most convincing theory on the origins and purposes of the round towers. Petrie then won the medal himself with his above-stated theories, which were formally published in an 1845 essay called ‘An Inquiry into the Origin and Uses of the Round Towers of Ireland; Comprising Remarks on the Ecclesiastical Architecture of Ireland Anterior to the Anglo-Norman Invasion’. The essay is published here.[2]

Petrie’s view of the round towers has been something of a gospel ever since, and his opinions will be found on most tourist sites and reference books, including Wikipedia and a number of my own pre-2024 musings.


Giant Towers and Mud Huts


On New Year’s Day 2024, I read an article called ‘The Round Towers of Ireland’ by Donald J. Bird, published by the New England Antiquities Research Association in their annual journal back in 1998. This had been forwarded to me by Clones-based historical sleuth George Knight.

Mr Bird felt it was time we questioned Mr Petrie’s findings. He reasoned that there were too many aspects of round towers that were underrated – the mathematical precision, the astronomical significance and such like. As an engineer, he was astonished by these extraordinary feats of engineering. These were built in an age when nearly everybody lived in a wattle hut or ringfort, with the occasional stone cottage in between. There were a few stone churches, but most were wooden, as were most palaces. And yet somehow the inhabitants of Ireland found the wherewithal to erect upwards of a hundred giant stone towers, each one requiring 15,000 ft.³ of rubble, rock and mortar, almost all of which had to be lifted ‘above normal reach.’




Round Tower, Castledermot

Round towers vary between 60 and 110 ft in height, with Kilmacduagh, near Gort, County Galway, having the tallest. The average is 90 ft, about the height of a nine-storey apartment block. There is so much weight in each tower that they are literally rock-solid, although one wonders how so many of them became ruinous, vanished or were otherwise reduced.  I won’t go into the details of diameters and such like here but Mr Bird observed that the foundations were generally about 4 ft deep and that the walls are generally a little less than 4 ft thick at the base and became slightly less thick at the top.

Each tower seems to have had between 5 and 7 wooden floors, supported either on a corbel ring jutting out from the wall, or by beams inserted into pockets in the inner wall.


The High Entrance


Why are the entrances to round towers generally about 10 feet above ground level? The traditional ‘Petrie’ answer is so that everybody could pile in with a rope ladder if the Vikings were on the prowl, yank the ladder in behind them and then wait for the threat to pass. I’ve never found that a convincing prospect. Surely, the Vikings would just smoke them out?

Mr Bird, with his engineer’s mind, offers a more practical reason. With each tower carrying such an immense weight of material, the builders had to allow time and space for the tower to settle. Any gap at the base for, say, an entrance, could have weakened the external walls with catastrophic consequences. To ensure stability, suggests Mr Bird, they placed the entrance higher up. As such, the ‘motive’ for these high-up doors was ‘stability, not security’ from Vikings (or other marauders), an opinion with which surveyor George Barrow concurred.

Mind you, I note that William Dalrymple’s ‘Holy Mountain’ has a brief reference to what he suggests was a practice in Byzantine Egypt of winching people into buildings to avoid capture by Bedouin tribes, so perhaps security was also an ingredient of sorts.


Astronomical Observation Platforms


Extracted from Donald J Bird, “Towers of Ireland,” showing orientations.

I am particularly taken with a theory, espoused in Mr Bird’s essay, that towers may have been observational platforms, located high above the trees, mists and smoky chimneys, providing astronomical knowledge to those within.

Most towers had four windows on the top floor, which generally seem to have been aligned with the cardinal points of the compass, while some had eight windows. (See Mr Bird’s chart of orientations opposite. Has anyone confirmed how many of the surviving towers are so aligned? Owing to the often early collapse of most corbelled tops, few upper storey was ever examined.)

Mr Bird quotes the American author Peter Tompkins (1919–2007), whose 1971 book ‘Secrets of the Great Pyramid’ noted how Ireland’s round towers were:

‘… carefully oriented openings at the top to observe the skies and record the passage of the days, months and years by shadows on the walls and floors.’

Tompkins adds that these ‘conical towers’, as he called them, were:

‘… fitted for Polaris observations at the north window, for transit observations at the south window, and for noting the moment of the rising and setting of heavenly bodies at the east and west windows … The walls being two or three feet thick. the solar shadows of the jamb and lintel cast upon the floor within would show the hour of the day and the time of year. Every month could have its transit floor mark.’

Mr Bird also refers to the Rev. Herman Gaylord Wood, a church architect and author of ‘Ideal Metrology in Nature, Art, Religion and History’ who proposed:

‘… threads drawn across the openings, like spider lines in a telescope could note the exact position of a star’.

When my colleague Michael Brabazon read Mr Bird’s essay, he wondered:

‘Could the towers be dual purpose? Built for astronomical observations (a gradual, learning, copying development) and then came in useful for other purposes. This would not be unlike the revised theory of evolution of certain features such as the giraffe’s long neck.  Rather than developing it in order to reach the higher branches, it is now thought that for some inexplicable reason the longness came about and then proved useful to get food from higher up.  We do the same with household objects – a screwdriver can become the thing that opens the paint can etc.’


Security System?


I am less convinced by Mr Bird’s theory that the round towers were all inter-connected as some sort of warning system, so that bells could be rung, or messages flashed, from one tower to another across Ireland. He suggest such information could be flashed at “an overall rate of perhaps 100 miles an hour, with hourly bulletins being provided.” They seemingly had something like this in the Loire Valley to alert people of Viking raids after the 840s. I did speak to a stonemason who wondered if there was a shutter system on the top-storey windows that allowed people to open and close a window, with a fire blazing on a brazier within, that would then blink – like the ingenious bicycle night light – to alert people that something was up or, perhaps, send coded messages across the land.

I’m open for most things but this still seems a slight far-fetched. For one thing, as Michael Brabazon observed, ‘a warning system would require a centralised political system that didn’t then exist.’ I’m not sure I fully understood Mr Bird’s thoughts on another traditional Petrie proposition that round towers were bell towers. He suggests that if they were bell towers, they would have had the bell at the bottom so that the sound would be amplified as it went up the tower and was then released out the upper windows. As bell metal was so precious in the medieval age, if there were bells within, then the Vikings (or others) would have been well up for plundering that, and breaking up the bells up if they were too big to get out of the tower doors … but again, I’m not convinced and, in any event, my understanding is that bells of that type were not invented until a later period.


A Celestial Map


The stars were assuredly aligning for me in early January 2024 because the very next day after I read Mr Bird’s essay, I saw a feature article by the Donegal-born writer and poet Eamon O’Caoineachan (Edward Keenaghan) on Irish Central about a possible round tower at Keenaghan Abbey in north-west County Fermanagh, which name-checked my brother Andrew Bunbury of the award-winning Park Hood, chartered landscape architects. Mr O’Caoineachan is working with Lisa McWilliams at Keenaghan Cottage and Stephen Heron at the Belleek History Society to prevent the area around Keenaghan Abbey from becoming a glamping site. Andrew seemingly prepared ‘a comprehensive landscape report that advocates for the protection of Keenaghan Abbey.’ In November 2023, Lisa launched a petition, accessible here, to protect the historic landscape around Keenaghan Lough and Keenaghan Abbey.

Mr O’Caoineachan’s article highlighted the work of another Irish American, Dr Philip S. Callahan, whose 1984 book, “Ancient Mysteries, Modern Visions: The Magnetic Life of Agriculture” observed a correspondence between the terrestrial and the celestial layout of the round towers, leading him to conclude that  the round towers were deliberately located ‘to match the night sky constellations.

Dr Callahan described the relationship between the stars and round towers thus:

“Of the four obvious alignments. Draco is the most perfect. Cassiopeia forms two Ws—one west to east and one north to south. Ursa Major (the Big Dipper) is slightly misplaced. Camelopardalis is also close to perfect. The ecclesiastical center of southern Ireland. Clonmacnoise, is the pole star. The ecclesiastical center of northern Ireland. Armagh, is the ecliptic pole. The round tower at Meelick [County Clare] is located at the star of Thuban, and Devenish Round Tower [County Fermanagh], my favorite, is located at the star Eta Draconis. Both were used to align the great pyramid”.

When I went back to George Knight with Dr Callahan’s proposition, he concluded:

‘That would explain how the very reason for their existence was lost in time. The influence of the incoming Cistercians and Augustinians, who would have had no truck with mysticism or astronomical practices. I would imagine the incoming continental orders regarded these towers as an example of pagan practices associated with the early Celtic church which they were in the process of reforming.’

The investigation continues.


Stray Thoughts


Michael Brabazon observes:

(1) Saxon monks came to Ireland for education, commencing with Mayo of the Saxons. Some writers believe that the round towers of Norfolk churches are originally Saxon design / construction. Could the Saxon monks have brought the idea, calling the structures bell towers / houses although they were never used as such in Ireland?  Like calling a copy email a cc (carbon copy) or referring to engine strength as horsepower?  An old word that is used without thinking …’. (eg: I still use the word walkman to describe my iPhone.)

(2) ‘Ref building in stone, the structures would normally supersede wood, hence woodhenge before stonehenge.  So the original purpose of the stone towers would lie in the wooden antecedents.  Saxons built special churches in stone, the rest in wood.’

(3) A theory espoused since the time of Jerome has suggested that Mary was called Magdalene because of her stature and faith, i.e. because she was like a tower, derived either from the Hebrew (Migdal, meaning “tower” or “fortress”) or Aramaic (Magdala, meaning “tower” or “elevated, great, magnificent”).

I wonder how the Tower of Babel story went down with Round Tower builders:

Now the whole earth had one language and the same words. And as they migrated from the east, they came upon a plain in the land of Shinar and settled there. 
And they said to one another, “Come, let us make bricks and fire them thoroughly.” And they had brick for stone and bitumen for mortar. 
Then they said, “Come, let us build ourselves a city and a tower with its top in the heavens, and let us make a name for ourselves; otherwise we shall be scattered abroad upon the face of the whole earth.” 
The LORD came down to see the city and the tower, which mortals had built. 
And the LORD said, “Look, they are one people, and they have all one language, and this is only the beginning of what they will do; nothing that they propose to do will now be impossible for them. 
Come, let us go down and confuse their language there, so that they will not understand one another’s speech.” 
So the LORD scattered them abroad from there over the face of all the earth, and they left off building the city. 
Therefore it was called Babel, because there the LORD confused (balal) the language of all the earth, and from there the LORD scattered them abroad over the face of all the earth.’
— Genesis 11:1–9

And how did they knock all those round towers down without killing everyone involved!! It makes me think of the steeplejack Fred Dibnah – watch him in action here.

Further Reading


  • Bird, Donald J. 1998. “Towers of Ireland.” NEARA Journal, Vol. 31, No. 2.
  • O’Caoineachan, Eamon, 2024, Is there a lost Irish round tower at Keenaghan Abbey?, Irish Central, 2 January 2024, here.



With thanks to George Knight, Michael Brabazon, Andrew Bunbury, Stuart Park and Éamon Ó Caoineachan (Edward Keenaghan).




[1] The suspected sites of 128 were surveyed by George Lennox Barrows between 1970 and 1978.

[2] The essay, published here, appeared in a book called ‘The Ecclesiastical Architecture of Ireland,’ as well as Transactions of the Royal Irish Academy, 20: iii–521.


Nelson’s Pillar, Dublin. A latter day round tower, also used for observation.