Kasteel de Haar is the grandest castle excursion near Utrecht, a theatrical neo-Gothic estate rebuilt around medieval remains for the Van Zuylen family. Turrets, moats, drawbridges, formal gardens, and richly furnished rooms make it feel closer to a storybook castle than a defensive ruin.
The castle is outside the city, but it is worth the trip for travellers interested in architecture, gardens, or aristocratic domestic life. Allow enough time for both the interiors and the grounds, since the landscaped setting is a large part of the experience.