Out in the green rolling fields of County Roscommon, near the little village of Tulsk, this landscape buzzes with a feeling much older than any history books. This is Rathcroghan (they also call it Cruachan Aí), one of Ireland's top ancient royal spots—a place full of deep mystery and old legends. It's not just one big impressive monument; it's a huge area of old sites, a big mix of man-made…