Lanterne de Rochecorbon, Medieval observation tower in Rochecorbon, France.

Lanterne de Rochecorbon is a 10 m high square stone watchtower, the only remnant of the medieval fortress of Rochecorbon, built at the south-west corner of the square walled enclosure. Its shaft of light grey and tan stone rises to a flat top edged by a slightly wider squared rim with a small projecting cornice, and a single narrow rectangular opening sits just below the top on one face. The base widens into thicker masonry merging with the cliff edge above the Loire.

Thibaud des Roches began building a stone fortress here in 1093 with permission from the Count of Anjou; Foulques IV seized it around 1100 before it was finished. His son Robert de Brenne resumed work after peace with the House of Anjou in 1133, replacing a wooden palisade with a masonry wall, and a chapel was built in the courtyard in 1157. The tower is the only surviving remnant of that castle.

The name Rochecorbon comes from Corbon des Roches, a knight living at Vodanum just before the year 1000 and nephew of Hardouin, Archbishop of Tours from 960 to 980. The village was called Roche Hardouin in the 12th century, then Vosnes-le-Crochet and Notre-Dame de Vosnes in the 15th and 16th centuries. The tower is private and not open for visits, but it is often opened to the public during the European Heritage Days.

The tower is private property and cannot normally be visited; it is usually opened to the public for the European Heritage Days. The site stands on a cliff edge above Rochecorbon, where the ground is uneven and the tuffeau rock is weakened by frost and cavities, so approach with care.

The tower occupies a precarious position on the cliff edge and faces ongoing threat from rock falls. This continuous geological change makes it a tangible example of the tension between preserving historical structures and the forces of nature at work.