A museum and art gallery in "desperate need" of renovation is to receive £400,000 towards the repairs from its owners Powys Council.
Brecknock Museum and Art Gallery was built in 1842
The local authority is also supporting a bid for hundreds of thousands of pounds of National Lottery funding for Brecknock Museum and Art Gallery.
Supporters said they were pleased work would finally go ahead on the Grade II star building in Brecon.
Its Victorian stonework and its leaking roof need repairing.
Powys Council said £250,000 would be spent on renovation work, while an additional £150,000 would go towards match funding a Heritage Lottery Fund grant.
Ken Jones, chairman of the Brecknock Society and Museum Friends, said: "We're very pleased something is being done to repair the building, which we consider is one of the most important civic buildings in Powys.
"The work is long overdue. For 30 years there has been hardly any maintenance work carried out and this has led to a leaking roof and the stonework crumbling.
"The museum is now in desperate need of repair."
Built in 1842, the museum and art gallery was originally a county hall and an assize court.
Its Grade-II star listing means it is a particularly important building of more than special interest, which categorises the slightly lower Grade-II listing.