Crest Castle is the ruin of a hilltop castle above the southern French commune of Crest in the Drôme department. Its preserved keep, at 52 meters high, is probably the highest in France and has been listed as a historical monument since June 1877.
Crest Castle was built in several phases from the 10th century to the second half of the 14th century. It was owned by the French crown from 1419 onwards. Louis XIII had it demolished in 1633, with the exception of the keep, which still stands today. The tower then served as a prison until the mid-19th century. In 1988, the commune of Crest acquired it from the French state. The tower has a floor area of 20 by 32 meters and a height of 52 meters. Portcullises, defensive bay windows, and loopholes bear witness to its past as a medieval fortification. The tower has 15 rooms, which were used as living quarters in the Middle Ages and as prison cells after 1633. Numerous graffiti date from this period, including those by Protestants imprisoned there.
Source: Wikipedia
A tour of the tower is open to the public. The current cost is €10 per adult.
The bravest can abseil down the tower's east wall from a height of 42 meters, but this wasn't possible during our visit, presumably due to a lack of tourists.