The remains of the Castle can be visited
Tour de Crest

The Tour de Crest is a castle ruin situated above the southern French commune of Crest. Its most striking feature is the preserved keep, which, with its height, is considered one of the tallest in France.
History+
The origins of Crest Castle date back to the 10th century, with its construction spanning various phases until the second half of the 14th century. In 1419, the complex became the property of the French Crown. By order of Louis XIII, the castle was razed in 1633, with only the keep being spared. This tower subsequently served as a prison until the mid-19th century. Since June 1877, it has been protected as a Monument historique. In 1988, the commune of Crest acquired the tower from the French state.
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: 44.7303, 5.0237