Other hotels in Waterford and Mayo make the top 10
Several Irish hotels have made it into a list of the top 50 best in the world.
The Ballyfin Demesne in Laois actually topped the list at number one.
Readers of US-based Condé Nast magazine voted in the 2016 Readers' Choice Awards.
Millions of ratings and over 75,000 comments were submitted.
On the Ballyfin Demesne, the publication says: "If you’ve ever dreamed of summering in a country house, you couldn’t do much better than Ballyfin Demesne".
The 20-room restored Georgian home is about an hour and a half north of Dublin.
"Inside there are gilded mirrors and four-poster canopy beds; outside, you can stroll the 614 acres of secluded private gardens, go horseback riding", it says.
But it adds that the real highlight is "having a butler row you out on the lake before enjoying a sumptuous lunch at the picnic house".
While Waterford Castle came in at number seven, and The Lodge at Ashford Castle in Mayo was voted number nine.
On praise for Waterford Castle, the magazine draws attention to "the ivy climbing the turreted stone walls of this stately 16th-century castle".
"In addition to the patterned brocade curtains, intricate wall tapestries, and refined Irish classics (caviar-topped smoked haddock, anyone?) at the Michelin-starred Munster Room".
The castle also sits on its own, 310-acre private island.
For The Lodge at Ashford Castle in Mayo, it says to expect something different.
"Don’t go expecting a fusty, old-fashioned experience: 2015 saw a $75 million renovation of the 13th-century estate, which allowed for such add-ons as a cinema, cigar room, billiard room, and dine-in wine cellars.
"Take the Cranki, the hotel’s 40-foot luxury Italian yacht, out on the river with seven of your closest friends", it adds.