As a last tangible reminder of the old village of Haarzuilens, one finds the Chapel next to the castle. The existence of this chapel is first mentioned around 1420, but it is likely that the chapel is even older; the tower still contains building remains of older date. Despite the fact that the population of Haarzuilens has remained overwhelmingly Roman Catholic throughout the centuries, the chapel passed into Protestant hands at the time of the Reformation.

During the 17th century, the building fell into more and more disrepair. After part of the roof collapses in 1703, the inhabitants of Haarzuilens use the tower and the remainder of the nave as stables and storerooms. Nevertheless, details of the Gothic wooden barrel vault will remain clearly visible under the remains of the rough wooden roof of the nave until well into the 19th century.

Baron Etienne van Zuylen decides not only to have his ancestral castle rebuilt, but at the same time to have the Chapel restored as the Castle Chapel. The choir and nave are built almost from the ground up, while in the transept old wall work is still incorporated. The whole is executed in neo-Gothic style. During the construction activities, mortal remains of, among others, ancestors of the baron were found in specially designed coffins.

The walls are adorned by a motley array of statues of saints, dating back several centuries. The oldest statues probably date back to the 14th century. Under the sacristy, a spacious crypt was built in the 1950s. Several members of the Van Zuylen family have since found their final resting place there. The tombs are inlaid with multicolored marble.

Today it is possible to rent the Chapel as a wedding venue. The centuries-old, atmospheric Chapel is characterized by serenity and elegant simplicity. The stained glass windows, medieval statues of saints and colorful paintings create a very special atmosphere. The Chapel can seat 120 guests.