In that year, the De Haar family received the castle and the surrounding lands as a fiefdom from Hendrik van Woerden.

The castle remained in the ownership of the De Haar family until 1440, when the last male heir died childless.

The castle is mentioned in an inventory of the possessions of Steven van Zuylen from 1506, and again in a list of fiefdoms in the province Utrecht from 1536.

The castle has 200 rooms and 30 bathrooms, of which only a small number on the ground and first floor have been opened to be viewed by the public.

The castle was equipped by Cuypers with the most modern gadgets, such as electrical lighting with its own generator, and central heating by way of steam.

[citation needed] The kitchen was for that period also very modern and still has its copper pots and pans, the largest extant set in the Netherlands, and an enormous furnace approximately 6 metres long, which was heated with peat or coals.

The tiles in the kitchen are decorated with the coats of arms of the families De Haar and Van Zuylen, which were for this purpose especially baked in Franeker.

The interior is furnished with many works from the Rothschild collections, including beautiful old porcelain from Japan and China, and several old Flemish tapestries and paintings with religious illustrations.

Surrounding the castle there is a park, designed by Hendrik Copijn [nl], for which Van Zuylen ordered 7,000 grown trees.

[3] After the death in 2011 of the last male heir, Thierry van Zuylen, his five daughters also sold the castle's art collection and furnishings to the new owners.