John F. Kennedy Arboretum
Ballysop, Ireland · built 1968
The John F. Kennedy Arboretum, on the Hook Head peninsula near New Ross, County Wexford, Ireland, is a park under public administration (owned by the Office of Public Works, managed by the National Botanic Gardens of Ireland), and a research collection of more than 5,000 varieties of tree and shrub. It is the largest such collection, by far, in Ireland.
BotanicalGarden data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).