Nantes castle was built by François 2nd, duke of Brittany,in 1466 when that province was still independent.
François 2nd was the father of Ann of Brittany, the beloved duchess, twice queen of France. Despite her political marriages with 2 kings of France, she loved both but made sure Brittany remained independent during her reign.
Unfortunately, only one of her numerous children lived, a daughter Claude, who inherited the dukedom. But she was very young when she was married to François 1er, king of France, and she had no choice but to sign the legation of her duchy to her husband, when she died; which she did out of exhaustion at the the age of 24, after bearing 10 children, from the age of 14! Thus ended the independence of Brittany.
The building you see on this picture, was erected by François 2nd of Brittany.But it was his daughter Ann who added the extra-floor with the 5 beautiful Renaissance dormer windows. The building was the living quarters of the dukes.