Subsidence caused by the widespread sub-surface mining in the surrounding industrial Ruhr area added to the structural damage, bringing the castle buildings close to collapse.
Only radical restoration measures taken by the Regional Association of Westphalia-Lippe (German: Landschaftsverband Westfalen-Lippe) from 1974 to 1989 saved the late Gothic castle complex from total decline.
As part of the powerful house of Nesselrode, he was steward for the Electorate of Cologne in the Recklinghausen district and expedited the modification and extension of the buildings in 1530.
The current owner is the Regional Association of Westphalia-Lippe (German: Landschaftsverband Westfalen-Lippe) which bought the then run-down castle along with the surrounding park in 1974.
[3] The Herten family built a medieval tower house in the first half of the 14th century, relics of which can be found in the vaulted basement of today's northern wing.
Herten castle bears resemblance to the Schloss Nordkirchen of that time, because they were built by the same architects: Henric de Suer and his son Johann.
This included removing fortifications from the complex and adding a ceiling fresco utilizing linear perspective in the great hall of the eastern wing.
He also added the elaborate portal on the western wing of the castle and ordered the creation of a French formal garden with numerous fountains and statues.
When the castle complex ceased being used in 1925, it was already in bad shape after being neglected by its owners and vandalized by French occupying troops.
[6] A considerable amount of original building fabric was beyond repair: the entire foundations as well as the ceilings were replaced by reinforced concrete structures and most of the castle was re-roofed.
Cartouches to the left and right of the portal tell about the families who resided at Herten Castle, the fire and subsequent reconstruction, along with the motto QUAERATUR VIRTUS – INVENIETUR HONOS (Search for virtue - and honor will be found).
When the chapel moved from Grimberg to Herten, the two decorated sarcophagi of Heinrich Knipping († 1578) and his wife Sybilla von Nesselrode († 1602) were also relocated.
The hedge maze no longer exists, but the open-air theater was reconstructed in a reduced form and is now used again for drama group performances.
Between the mid-19th century and the First World War, the castle's owners laid out two fish ponds and a mixed forest of approximately 200 hectares (500 acres).
When the Regional Association of Westphalia-Lippe (German: Landschaftsverband Westfalen-Lippe) stepped in to save the castle from total collapse in 1974, the park had also been neglected for over 50 years and looked accordingly.
[3] These exotic plants were brought to Herten by the castle's former owners upon returning from diplomatic missions in distant countries.
The front of ten windows was crowned by a balustrade with twelve life-sized sandstone statues representing figures of Greek mythology.
A square garden pavilion in the eastern part of the park is called "Tabakhaus" (tobacco house) and commemorates two counts of Riaucourt who were sons of a countess of Nesselrode and fled to Herten when the French Revolution swept through their home country.
While living in Herten, the two counts smoked tobacco in the "Tabakhaus" since it was regarded as a new-fashioned sin and not permitted in the main castle.
The vaulted castle basement contains an exhibition by the German "Nature and Biodiversity Conservation Union" NGO showcasing the flora and fauna of the park.
The carriage house is used as a social center and day hospital of the adjacent psychiatry and psychotherapy clinic run by the Regional Association of Westphalia-Lippe.