More than £5m of council money is to go towards a major revamp of a Victorian museum and art gallery and a new library in Brecon.
It comes after Brecon Museum and Art Gallery was awarded £2.5m from the Heritage Lottery Fund (HLF) in July.
Powys council's cabinet said the changes would cost £7.6m in all.
Up to £4m of the council's funding will come from the sale of buildings in Brecon.
The HLF regards the Grade II-listed building as one of the finest examples of early Victorian Greek revival architecture in Wales.
It houses one of the largest art collections in Powys but the former court and shire hall needs repairs to its stonework and roof.
The cabinet approved plans to spend more than £5m renovating the Brecon landmark and building the library.
Powys council's cabinet member for regeneration, Rosemarie Harris, said: "Brecknock museum has played an integral part in the town's landscape for nearly 200 years and our plans will allow it to continue for many more years.
"The restoration will provide impetus to the regeneration of the area and a much-needed financial boost to the economy in the town and the surrounding area."
The museum and art gallery revamp and the library form part of wider plans for a cultural and community hub in the town centre.
The proposals include a dedicated learning space, the expansion of the education and outreach service and new digital equipment to help with presentations.
In July, the HLF said its funding would help safeguard the museum and art gallery, which was originally built in 1842, for the future.
Powys council first applied for the lottery funding for the museum and art gallery in 2009 but the bid was rejected.