>>520485516
The best I tracked is that this data comes from OpenStreetMap with a tag "castle"
And I quote
>The scope of the tag currently also includes non-fortified residences like palaces
In the data, you have included
>[W] Stately homes ([W] châteaux) and [W] manor houses: Unfortified residences of a lord, a noble or a gentry.

You also have actual castles in the data, it's just not a map of castles.