A Jacobean mansion and a concert venue in a Baroque church are among 26 sites across London to be added to Historic England's at-risk register.
Charlton House in Greenwich, south-east London, was built in 1612 and repaired following damage caused in the Blitz, but a leaky roof is affecting its historic interior so it has been added to the register.
Twenty-five other sites have been removed from the list as they are now considered safe, such as Abney Park Cemetery in Hackney. Another place was cut after being reassessed.
It means there are now 599 sites across the capital deemed at risk of neglect, decay or inappropriate development by the heritage group.