The high-value items were taken on 25 September between 1am and 2am, prompting an appeal for information from Avon and Somerset Police.
Police have released CCTV footage of four individuals they believe can assist with their investigation into the theft.
Detective Constable Dan Burgan described the theft as a significant cultural loss, saying that the items provide insight into a multi-layered part of British history.
Members of the public are urged to contact the police if they recognise the men pictured or see the stolen items being sold online.