A museum and art gallery in Powys which is in need of restoration is planning to apply for hundreds of thousands of pounds of National Lottery funding.
Brecknock Museum and Art Gallery was built in 1842
Supporters of Brecknock Museum and Art Gallery in Brecon, said the Grade II star building was important to the county.
But the Victorian stonework is crumbling and its roof is leaking.
Powys Council, which owns it, is to decide whether to formally back the lottery bid.
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.
Ken Jones, chairman of the Brecknock Society and Museum Friends, said: "It's probably the most important and historic civic building in Powys.
"But the stonework in crumbling to such an extent that netting has been placed around the top of the building.
"The roof is leaking in various places too."
Mr Jones said repairs to the stonework had been estimated at £400,000 two years ago, and he felt that the roof could cost up to £300,000 to renovate.
Powys Council said a meeting would be held shortly to discuss the museum and art gallery.