This is one of Europe’s most outstanding tree and shrub collections, situated amid a breathtaking mountain and seascape. Because of their beauty, vitality, and perfect form, the trees in the National Arboretum attract tree enthusiasts from all over the globe. Castlewellan, on the other hand, has a variety of distinguishing characteristics that draw notice. The garden is a mix of casual and formal designs, including terraces, fountains, ornamental gates, and flower borders. A mile-long walk around the forest park’s lake, passing by some stunning contemporary sculptures along the way, is a great opportunity to observe eighteenth-century horticulture.