The Castle can be visited
Château de La Roche-Guyon

In France, in Val-d’Oise in the Île-de-France region, the Château de La Roche-Guyon is situated. It is an example of the combination of medieval defensive architecture and later castle construction, partly carved directly into the rock.
History+
The origins of the Château de La Roche-Guyon date back to the 10th century, when a castle was built on a limestone cliff above a bend in the Seine at this location. It served as a border fortification in conflicts with the Normans and was repeatedly reinforced. The noble family of La Roche, who bore the first name Guy, gave the place its name. This family was succeeded by the Silly in the late 15th century, who were elevated to counts in 1515. Later, the property passed to the La Rochefoucauld family, who received the ducal title for La Roche-Guyon in 1622. In the 14th century, a manor house was built at the foot of the cliff, connected to the upper castle by a secret passage.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Hervé Rebours
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 49.0812, 1.6279