The arboretum runs along the banks of the Gyöngyös brook alongside the castle, and contains several hundred tree species and varieties collected over more than two centuries. The star specimens are a 36-metre pyramid oak — one of the tallest in Hungary — and several English oaks believed to be over 400 years old, planted when the Nádasdy family was at the height of its power. In autumn the colour along the brook is exceptional.
The arboretum is free to enter and makes a natural extension to a castle visit — they share the same grounds. It is also a popular spot with local families, particularly on summer evenings. The combination of the shaded woodland paths, the brook, and the castle towers visible through the trees makes it one of the more pleasant green spaces in western Hungary. The Forestry Museum on the edge of the arboretum covers Hungarian forest management and woodland ecology.