Original technical plans for the crane used to build the Titanic have been discovered in Northern Ireland.
The Titanic sailed from Belfast in 1912
The linen-backed plans are the only known copies in existence.
They came to light at a Titanic exhibition currently being held in Belfast, where the ill-fated liner was built.
The Titanic was built at the city's Harland and Wolff shipyard and sailed from Belfast in 1912. It sank after striking an iceberg.
The 150-tonne crane was built in Germany to specifically construct the Titanic and her sister ships in Belfast.
It arrived in Belfast in kit-form and German workers installed it at Queen's Island in the shipyard.
The plans were originally used as a file copy for engineers to work on the crane's construction.
They were brought along to the "Titanic - Made in Belfast" exhibition for evaluation by a member of the public.
Auctioneers who specialise in Titanic memorabilia held an open evaluation in Belfast City Hall earlier this week.
Evaluators Henry Aldridge and Sons predicted a four-figure sum for the plans when they go for auction.
The company's Alan Aldridge said: "On presentation by the owner, we knew this was authentic and of the Titanic period given its look and feel - it even has a reference to the Lusitania, the biggest ship at the time, on the plans.
"For us, this is an absolutely fantastic find and we would like to think there are many more hidden gems waiting to be discovered in the city of Belfast."
The rare plans have gone on display at the event in the City Hall.
Belfast City Council said it was "truly an exhibition which could not be staged anywhere in the world but the home of the Titanic".