Nearly 800 historic buildings in London are at risk from decay and neglect, according to English Heritage.
Broomfield House was damaged by a fire in 1984
The organisation says 71 buildings have been added to the latest Buildings at Risk Register while 96 have been removed.
The latest list includes Broomfield House in Enfield, north London, and Crossness pumping station in Bexley, south east London.
English Heritage said London has about 40,000 listed buildings, of which around 2% are at risk.
The register was first compiled in 1991 and 90% of the buildings on that first register have been saved.
But English Heritage said it did not have the resources to save some nationally important historic assets.
More resources needed
Philip Davies, regional director for London, said: "We offered £4.5m in grant aid to buildings at risk in London last year, but this is a very small sum when you consider that many individual buildings, such as large churches or mansions in public parks like Broomfield House, often need more than £1m each for repairs.
"If more heritage resources are not made available, many of London's most important and vulnerable architectural icons will pass the point of no return."
He said buildings often fell into the "at risk" category because of lack of money for maintenance when ownership changed or when the building was no longer needed for its original purpose.
Broomfield House stands in its own park in Enfield
Broomfield House, a 16th Century Listed Grade II house, has been damaged by a number of fires.
For centuries, it was a family home for a succession of City merchants.
In the 20th Century it was a school, and later a health centre until it was damaged by fire in 1984.
Crossness pumping station, a 19th Century Grade I listed building, is described as a "spectacular cathedral-like building with magnificent Victorian iron work".
It has four beam engines by James Watt and Co and is currently being run by volunteers.
Among the buildings removed from the list is Eltham Orangery near Greenwich and St Luke's Church, Islington, which has been converted for use as a rehearsal space for the London Symphony Orchestra.
The register is intended to keep attention focused on neglected historic buildings and monuments.
It is designed to define the scale of the problem and to prioritise action by English Heritage, local authorities, building preservation trusts and funding bodies.