The theatre at Craig y Nos Castle was revolutionary at the time and is now of great historical interest for several reasons:
(1) It is the only opera house ever built by an opera star / opera performer.
(2) It is one of only 8 Grade One listed Theatres in Britain, and one of only two in private ownership.
(3) It is Grade One listed thanks to it being 'frozen in time' in 1919 when the castle became a TB Hospital. Where most theatres tend to continue in use, evolving as new technology replaces old, before finally falling out of use and coming under redevelopment, the theatre at Craig y Nos ceased being used as of 1919 as a theatre. However, rather than being redeveloped, crucially it was preserved intact by the Hospital Authorities who used it as a TV room for patients and staff.
Virtually every piece of working machinery that was in place in 1919, is still there, unchanged, now. Theatre experts visit and study the stage flooring, backdrop and ropes and pullies, able to understand exactly how each piece would have been operated historically.
(4) It is one of the first theatres to have an ascending / descending auditorium, so when in its sloped (raked) position, it acts as a theatre, and when in its flat position, the room serves as a ballroom. It is mainly used as a wedding ceremony room now, but is open for performances and recording artists to use as well.
(5) The floor, all the internal walls, panels and Corinthiam columns are entirely built out of wood, with the wall panelling, its shape and the size of the room so arranged as to create a space renowned for having the most excellent acoustics. The quality of the acoustics in this theatre are particularly good, indeed they are considered among the best of any theatre in the UK. For this reason the theatre is popular with recording artists and remains available for further recordings.