Solidor Tower is a strengthened keep with three linked towers, located in the estuary of the river Rance

Rance

is a series of Japan-exclusive eroge computer role-playing games by Alice Soft featuring the title character, Rance. Starting in 1989, the series has lasted for 20 years, making it one of the longest running adult themed games ever.-Rance:...

 in Brittany

Brittany

Brittany is a cultural and administrative region in the north-west of France. Previously a kingdom and then a duchy, Brittany was united to the Kingdom of France in 1532 as a province. Brittany has also been referred to as Less, Lesser or Little Britain...

.

It was built between 1369 and 1382 by John V, Duke of Brittany

John V, Duke of Brittany

John V the Conqueror KG was Duke of Brittany and Count of Montfort, from 1345 until his death.-Numbering:...

 (i.e. Jean IV in French) to control access to the Rance at a time when the city of Saint-Malo

Saint-Malo

Saint-Malo is a walled port city in Brittany in northwestern France on the English Channel. It is a sub-prefecture of the Ille-et-Vilaine.-Demographics:The population can increase to up to 200,000 in the summer tourist season...

 did not recognize his authority. Over the centuries the tower lost its military interest and became a jail. It is now a museum celebrating Breton sailors exploring Cape Horn

Cape Horn

Cape Horn is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island...

.

The Solidor tower is located in the former city of Saint-Servan

Saint-Servan

Saint-Servan is a town of western France, in Brittany, situated 2 miles from the ferry port of St Malo. It is renowned for its lovely shops and restaurants....

, which merged with Saint-Malo in 1967.

It is featured in the 1956 Wendy Toye film True as a Turtle starring John Gregson, Cecil Parker, June Thorburn and Keith Michell http://www.imdb.com/title/tt0049886/.