The Kennedy's, New Ross
Patrick Kennedy, JFK’s great- grandfather, left Ireland in 1858. Distant relatives have turned the property into a little museum / shrine for Kennedy pilgrims. Physically, it’s not much: A barn and a wing of the modern house survive from 1858. JFK dropped in by helicopter in June of 1963, a few months before he was assassinated.
Probably not really a 'must', but maybe one or another is interested.