Conservation work at the 800-year-old Johnstown Castle in Co Wexford has revealed a "secret room" that is thought to have been untouched for decades or longer.
The gothic-revival castle outside Wexford town has been undergoing substantial conservation and restoration works in recent years.
It has been reopening to the public in stages, but a new discovery was made at the weekend when a carpenter working on a window found the room.
It will now be assessed by the Irish Heritage Trust, in whose care the castle rests, to find out more about what it was used for, when and by whom.
The trust will also examine how it can be used to benefit the castle in the years to come.
Contractors from the National Gates and Joinery Company, who are involved in the restoration work at Johnstown, broke through a section of wall at the weekend and then found the hidden room.
"This is a really incredible discovery," said Irish Heritage Trust CEO Anne O'Donoghue.
"It is highly unusual to find additional hidden treasures in heritage properties and this is the second time that this has happened at Johnstown Castle following our discovery of a secret room under the tower at the lake just last year."
That room found under the tower is only accessible by boat.
"The trust's mission is to care for the properties and work towards making them financially sustainable.
"This is done through a number of different ways, such as welcoming visitors to our sites, philanthropy and competitive grants.
"In the case of the windows here in Johnstown Castle, the work are been completed with support from the Department of Heritage," Ms O'Donoghue added.
Parts of the castle were opened to the public for the first time in mid-2019.
More followed during the last two years, following a €7.5m makeover, which included the construction of a new visitor centre and restoration of an 86-metre underground servants' tunnel.
Johnstown Castle and Estate had been in private hands for centuries and was owned by a number of different aristocratic families before entering public ownership in the late 20th century.
The East Wing, whose renovation was completed last April, includes a ballroom, oratory, billiard room, and science laboratory across three floors.
Manager at Johnstown Castle Brenda Comerford said the just-discovered hidden room was covered "for a very long time" until the weekend.
She added: "It is part of one of the towers and looking around it, on initial inspection we think it was most likely a small turret bedroom.
"There is quite a tragic family history associated with Johnstown Castle, so this room could have been sealed off due to a tragedy, which would have happened in times past, who knows. We will need to investigate this further."
