10. Rathfarnham Castle
Kicking off our tour of amazing castles in Ireland, we have Rathfarnham Castle. It was built for Archbishop Adam Loftus, a key player in the establishment of the Trinity College Dublin. During the 18th century it was transformed by James Stuart and Sir William Chambers, two of the leading architects of the time, into a Georgian manor house. They also removed the defenses and fortifications, which were, of course, unnecessary by that point. The castle is now under active conservation, and tourists can see it between the months of May and October.