The fortifications at Dover's Western Heights are in urgent need of repair, costing up to £1 million.
That's according to the latest "Buildings at Risk" register, published by English Heritage on Tuesday.
The register records that the extensive fortifications are in multiple ownership.
The parts at risk include the western outworks, on land managed by the Home Office, and the north entrance, north-centre bastion and adjoining detached bastion, which are looked after by English Heritage.
Although these are described as "robust", they are said to be steadily deteriorating due to long-term neglect and vandalism.
Another building on the register is the Belvedere at Waldershare Park. Built from 1725 to 1727 by Lord Burlington for Sir Henry Furnese, it has been derelict for many years and is now said to be "in a ruinous state".
