The duke was also shown files relating to his parents’ visit to Belfast in 1941 in the aftermath of a Luftwaffe bombing raid.
The Duke of Gloucester learned about the history of Belfast during a visit to mark the 100th anniversary of Northern Ireland’s public records office.
The duke enjoyed a tour of the Public Records Office of Northern Ireland (Proni) in the capital’s developing Titanic Quarter on Friday.
He was shown some of its oldest documents, including a papal bull dated 1219.
The duke was also shown files relating to a visit by his parents, Prince Henry and Princess Alice, to Belfast in 1941 in the aftermath of a devastating Luftwaffe bombing raid on the city.
The city was hit by a blitz in April and May of that year, during which 900 died and 1,500 were injured.
The duke also met staff and the public during his visit, and was shown Proni’s stores and conservation laboratory.
He concluded his visit by unveiling a commemorative plaque.
Acting director of Proni David Huddleston said they were delighted to host the special visit.
“It was a great opportunity for colleagues to showcase the work of the Public Records Office and the duke showed a keen interest in the archives and the important role they play in our community,” he said.