The actor bought 15th century Kilcoe Castle at the end of the last century and has spent all his spare time revamping the old building ever since.
He admits it was a labour of love, but it wasn't always an easy job.
He tells Parade magazine, "Renovating scared the wits off me. I didn't know what it was going to cost or how long it would take, or that I'd manage to do it. People were sort of surprised, 'cause they think I'm an extremely wealthy actor. They thought, 'You'll get architects in, you'll get builders, and they'll do it.' But I didn't want to do it that way. I wanted to be as hands-on as I could."
And Irons admits he's glad he dismissed initial ideas to modernise the castle - because they would have ruined the old place.
He adds, "I didn't put a lift (elevator) in. The purist inside me said, 'You've got to earn that height. If you want to get up there, you've got to walk.'
"I'm sort of glad about that, even though when I'm 80 I may be cursing that decision."