Ninety-nine of Ordnance Survey's Landranger/Discover maps were used to collect these forts and the other maps are currently being surveyed to collect details of the many others – see How it Works for more details.
Our aim is to be as accurate as possible and, if you do see some errors, please do let us know and we can make the alterations. Many thanks.
Where available, official sources of historical information for a fort are also provided.