Is Château de Brissac haunted?
France Reported haunting level 4 of 5

What actually happened
Charles II de Cossé began a grand reconstruction in 1606 that halted at his death in 1621, leaving the château only partly rebuilt.
The history
Fulk Nerra fortified the site in the 10th century, Pierre de Brézé rebuilt it from 1434 and René de Cossé bought it in 1502. The Cossé-Brissac family still own the seven-storey château of 204 rooms.
What people report
The château's own history tells of Charlotte de Brézé, killed with her lover by her husband Jacques, whose restless soul is said to wander the rooms on fevered nights; visitors call her the Green Lady.
That paragraph is reported tradition, not a claim about what is there. The history above it is sourced; the stories are recorded because people tell them.
Visiting
Château de Brissac, 49320 Brissac-Loire-Aubance, France