The concept of “nose blindness” was introduced to us in Febreze marketing campaigns in the late 2000s. It suggests that we can adapt to unpleasant smells in our homes – wet dog, teenagers’ socks, towels left in the washing machine for half a day too long – to the point where we no longer notice them.

The ads have been effective enough over the years that I have worried about my own potential nose blindness, although guests have assured me there is no hidden pong to worry about. Recently, I’ve become concerned that I’m suffering from a different affliction: castle blindness.

I’ve been labouring under the assumption that there are maybe 15 castles in Ireland. There’s the one Enya lives in, the one Jeremy Irons lives in and then a gaggle of other historical tourist spots and wedding hotels making up the numbers. It has always puzzled me when Americans come to Ireland to see “the castles”, and I worry they will be disappointed when there isn’t a turret poking out at them around every bend.

With the news that Meta chief executive Mark Zuckerberg has purchased Strancally Castle in Waterford, an enormous 1847 mansion on more than 400 acres that I had never heard of, I became concerned I might be absolutely riddled with castle blindness.

Castle ruins do dot the Irish landscape, but I fear I’m completely environmentally numb to them. A tourist driving through the country might point with glee at a crumbling tower in a field surrounded by unimpressed Friesians while I simply don’t register it at all. A quick Google tells me there are 30,000 castle sites and ruins in Ireland!

In fairness, the term “castle” might be doing a lot of heavy lifting. When we think “castle” we think vast buildings with high curtain walls and moats and battlements, but it seems that between the 1400s and 1600s the Normans could be throwing up any old one-family tower and calling it a castle. Most of these structures, along with a great deal of their more impressive counterparts, have fallen to ruin thanks in part to our old pal Cromwell.

I’ve decided to embark on an autumn project to attempt to cure myself of my castle blindness. I’m going to start with some of the biggies, to get my bearings. Drimnagh Castle is less than a 10-minute drive from my house, and to my great shame I have never visited. The website tells me it is available for hire for photoshoots for €200 an hour. Do I have an Instagram carousel in my future featuring multiple damsel-in-distress poses? Could Norman knight Hugo de Berneval, who built Drimnagh Castle in 1240, ever have imagined his great fortress would one day sit close to an Aldi and be within spitting distance of the Walkinstown Roundabout?

Emer McLysaght: 'Drimnagh Castle is less than a 10-minute drive from my house and to my great shame I have never visited.'Emer McLysaght: ‘Drimnagh Castle is less than a 10-minute drive from my house and to my great shame I have never visited.’

My home county of Kildare seems to be teeming with castles. The ruin of Kilteel Castle, which is just a few minutes’ drive from where I grew up, is a 15th century, five-storey fortress with a round tower that was important in defending the border of The Pale. I plan to pay a visit and see whether there is anything to be done with it with a vacant property grant. Bet I could get that Ber rating right up there.

The National Monuments Service has an interactive historic environment viewer map that documents archaeological sites, monuments and heritage structures. The map is littered with red and blue dots that might be anything from a standing stone to a castle ruin. I’m going to be flat out noticing things and finding them on the map. Castle blindness begone!

Zuckerberg’s Waterford castle grab is likely a status symbol acquisition, as much as it sits a handy-ish commute from Meta’s headquarters in Dublin (I’m sure he has his own helicopter at hand). There aren’t many regular Irish families who could afford to purchase, renovate and maintain a castle so, while it’s always unsettling to see international billionaires buying up pieces of Irish history, the reality is that without these kinds of property deals, some of our most impressive structures would be in ruins like so many others.

Tycoon towers: Irish castles and houses owned by the global super richOpens in new window ]

Just think, in the 30th century the records will show that “in 2026 tech wizard Mark Zuckerberg took ownership of Strancally Castle in Co Waterford, having made strategic inroads in Ireland to exploit its educated workforce and corporate tax environment”. That is, of course, if the earth and the records survive the data centres. Maybe the data centres will be the blue and red dots on the interactive map… I shudder at the thought.