Brecknock Museum and Art Gallery was built in 1842
Plans for a £5m revamp of a Powys museum are in tatters after a council failed to secure funding from the Heritage Lottery Fund (HLF).
The Grade-II star listed Brecknock Museum and Art Gallery in Brecon needs repairs to its Victorian stonework and its leaking roof.
Powys council said its application for £2.5m from the HLF had been rejected.
The HLF said after careful consideration it could not support the project.
In recent months several ideas about how to restore the museum and art gallery have gone on display at an exhibition.
Hopes were that the council could secure £2.5m from the HLF and then match fund the money.
The local authority said it was disappointed its bid had failed.
A spokesman added: "The council submitted a £2.5m bid to Heritage Lottery Fund to help redevelop and restore Brecknock Museum and Art Gallery.
"The council has received an indication that the application has been unsuccessful but has not yet received any detailed feedback on the submission.
"It is too early to say what the decision will mean to the full project."
On its website, Powys council said the museum and art gallery was "one of the finest and liveliest small museums in Wales".
Jennifer Stewart head of the HLF Wales said after careful consideration it could not support the council's application.
She added: "We were impressed with the council's plans to conserve and reinvigorate Brecknock Museum and Art Gallery, a popular local resource within the historic town of Brecon.
"This was a highly competitive round of decision-making for us and, sadly, we just didn't have enough money to support all the applications we looked at on the day."
Built in 1842, the museum was originally a county hall and an assize court. It was opened as a museum in 1928.