Information for Dark - Temporary Building Closure at St David's Hall, Cardiff (Unknown). When a theatre is 'dark' it means that it is closed. This may be temporary, e.g. between shows, or it may be semi-permanent, e.g. when it is closed for refurbishment (sometimes it is uncertain when this happens whether it will actually open again) and sometimes it means that the theatre is completely out to action, lost or gone! Following a building survey the presence of Reinforced Autoclaved Aerated Concrete (RAAC) has been discovered, consequently the building has been temporarily closed for the month of September. 18 Month extension notified on 16 Nov 2023.