Castles and structures of Estalia
Grobius Shortling was an aficionado of British History and architecture. He used his love of both to flesh out the castles, towers, and towns of his imaginary countries of Estalia and Almondsey.
The main page of his work can be found at http://www.estalia.net/estalia/estaliapage.htm
On that page are links to scores of palaces, fortresses, castles, towers, cathedrals, taverns, and towns. Although all the plans were done in MS Paint, Grobius got the absolute maximum out of the program. Check out his plans for the Hierophant's Castle http://www.estalia.net/estalia/hiero.htm, Castle Paladrian http://www.estalia.net/estalia/paladrian.htm and Chateau Nuorgk http://www.estalia.net/almondsey/nuorgk.htm among many, many others.
And if all that isn't enough, Grobius has a second, separate site devoted to imaginary castles at http://www.estalia.net/imaginary/index.htm.