54 places across the South West have been added to Historic England's annual Heritage 'At Risk Register'.
They include Malmesbury Abbey in Wiltshire, King Arthur's Great Halls in Tintagel in Cornwall, Bristol townhouse Kingsley Hall and High Angle Battery on Portland Harbour.
They have been added to the register because of concerns about their condition, and Historic England said they are at risk of being lost forever as a result of neglect, decay or inappropriate development.
The organisation has awarded almost £1m in repair grants for the sites.
But it also said more than 80 historic sites have been saved.
They include Britain's oldest lido, Cleveland Pools in Bath, which reopened in September.
Rebecca Barrett, Regional Director at Historic England said: "It is central to Historic England's mission that we pass on to future generations the rich legacy of historic buildings and places that we have inherited from previous generations.
"Our Heritage at Risk programme is a key contributor to this ambition.
"With the help of local communities and partners, imaginative thinking and business planning, we can bring historic places back to life in the South West.
"It is truly heartening to see how people across the region have come together to save the places they love - from the Stowey Green Spaces Group to the supporters of the Cleveland Pools project. Their pride in place is evident and key to their success.
"But as the 54 new entries on our Register show, there are challenges ahead for many communities.
"Strong partnerships with supporters, funders, conservation specialists and skilled craftspeople remain crucial to securing the future of many historic sites and places in the future."