When it comes to choosing the best hotels in Ireland, it's a toss-up between old and new. Even the most historic Irish castles are moving with the times, impressing with their commitment to sustainability and fully rooting guests in a slow-travel scene. Elsewhere, there are Victorian piles newly hung with Warhols, country-house stalwarts flaunting their Michelin stars, original game-changers quietly championing the best farm-to-fork ingredients and revamped spas reflecting the rise and rise of wellness. This being Ireland, wherever you check in, the slickest service will be delivered with down-to-earth charm.