First, there's the color.
To call Ireland green is to commit glaring sins of omission. It is the sort of green reserved for gods and Pantone swatches. Kelly green, acid green, the greens you see in jars of pure mineral pigment, greens that blow out your photos the way that red roses or blue skies do. Green as primary color.
View from Kilcrea Castle Ruins, County Cork
When I lived in Oregon, I thought it was green, and then I moved to North Carolina and realized that it had been grey-green. North Carolina, I thought, was green. Then I went to Ireland. Now I see how yellow the undertones here are, and how desaturated the greens are by comparison. Fortunately, I am told that the only color that compares to Ireland is in the depths of the rainforest, so it will stay green in my head for a long time.
Also, as with so much of Europe, things are relentlessly old. I stood on the battlements of a ruined castle built at the same time as Blarney Castle and I could see three other ruins from the top. "Oh," said my friend Carlota, "that's the NEW ruin, over there..." Eventually it became a running joke--"Oh, that's the NEW standing stone..." It became exciting when the new building wasn't old than my country. Occasionally they predated Europeans in North America at all.
Yes, I'm including the Vikings.
But possibly the most intense thing was simply that it was relentlessly, savagely picturesque. You could point your camera in any direction and come away with a postcard. It was beautiful, and it kept being beautiful, and eventually it got to the point where you would look over the view and start swearing, because it was being beautiful again.
After awhile, you stopped going "How lovely!" and started going "How do people stand this?"
(I asked Twitter. Residents uttered some variation on "Whiskey" and "You get used to it, but whiskey helps.")
You just have to figure that sooner or later, living in that kind of beauty would weigh down on you, and you'd either become hard as diamond or break and become a poet. It's just...intense. I think of people who left there--my ancestors, some of 'em--to come to America because of poverty or starvation or hope or whatever, and I can get just the smallest glimpse of what that must have been like--enough to know what I can't really imagine what it was really like. America is beautiful, don't get me wrong! (I believe there's a song about it.) But it's a completely different sort of beauty, a sort that doesn't much care about the people on it. If we all died tomorrow, I doubt America would even notice much, but Ireland would be sad that the people were gone. It's the difference between the Rockies and a green field with a black horse grazing surrounded by rooks, under a hill covered in mist. They're both beautiful, it's just...scale.
I don't know. Maybe I'm raving. I am only a tourist and don't pretend to know anything about what life is really like there. It was just...so intense.