The building was an early Victorian country house built on parkland beside the River Tawe. The main building was built during the period 1841 - 1843 by Captain Rice Davies Powell. It was said that his family were cursed and he went blind and insane. It was later bought by Morgan Morgan who lived there for some time and his son of the same name. Adelina Patti purchased it in 1878 to develop it as her own private estate. Patti later added several features to the building. After Adelina Patti's death, the house was sold in 1922 and was used as a tuberculosis sanatorium for 60 years, during which time it fell into disrepair. In the 1980s it was bought by a consortium of businessmen who formed the Craig y Nos Castle Company and began a process of restoration work on the buildings. The following decade it was purchased by SelClene Ltd, which continued the restoration and opened the castle as a hotel.
Adelina Patti Theatre
One structure of note is the Adelina Patti Theatre, a Grade I listed opera house built by Adelina Patti. It was built to be Patti's own private auditorium. The theatre was opened on 18 July 1891. It was modelled as a miniature version of La Scala, Milan and holds an audience of up to 150 people. The auditorium floor can be raised level, for use as a ballroom, or sloped towards the stage, when in use as a theatre. The opera house is licensed for weddings and is still occasionally used for public performances.
The castle is said to be subject to strong paranormal phenonemon and haunted by the ghosts of Patti, her second husband, French tenor Ernesto Nicolini, and the object of her affection, composer Rossini. Unexplained presences have been experienced by visitors all over the castle in many different forms. Nurses who worked at Craig-Y-Nos while it was a hospital have reported many presences and frequent reports of "having walked past somebody on the stairs or corridor but nobody being there" and many unexplained noises and sounds of footsteps. Visitors have also said to have experienced breathing difficulties and to feel a lingering presence of old patients who were hospitalized there suffering from tuberculosis. On one occasion a crew were recording an interview in the theatre and while in the kitchen they were discussing the fact that Adelina Patti had never mastered the role of Carmen. Suddenly a heavy saucepan flew onto the floor which had been placed on a large cooker, far enough away from the edge.
The building was subject to an investigation on Living TV's Most Haunted.