Activists will take part in a march today in protest at cuts to libraries, museums and galleries.
Unite, Unison, and the Public and Commercial Services (PCS) union warn of a "national crisis", saying more than 340 libraries have been closed in six years - losing a quarter of staff.
Unite officer Fiona Farmer said ahead of the demonstration in London: "Tory Government cuts to local government funding have wrought havoc to our public libraries with hundreds closing.
"What we are seeing community by community is an act of cultural and educational vandalism.
"Libraries are the gateway to knowledge, learning and enjoyment for all ages of people from all walks of life.
"Yet more and more communities are seeing their library disappear or service diminish because of librarian cuts or failed privatisation."
As well as pay and jobs being cut, many museum and gallery visitor services are being privatised, say the unions - as organisations look for short-term measures to cut costs.
PCS general secretary Mark Serwotka said: "Given the clear benefits arts and culture bring to our society and our economy, cuts to libraries, museums and galleries represent everything wrong with the Tories' approach to public spending.
"While institutions are closing, privatising services or charging for access, the staff who guard our nation's cultural treasures are languishing on low pay and insecure contracts."