Tattershall Castle was originally built as a stone house by Robert de Tattershall in 1231 in the current town of Tattershall, Lincolnshire.
The Great Tower as it currently stands (the walls and outbuildings are mainly destroyed) was built by Lord Ralph, 3rd Baron Cromwell (at the time the Lord Treasurer) between 1430 and 1450 and restored by Lord Curzon of Kedleston at the beginning of the 20th century.

I built this model alone in creative mode and used worldedit for the moat. 
The model is quite realistic for the small scale it is on and includes the parlour, the great hall, the audience chamber (including 40 historical county flags), the privy chamber, 13 extra rooms, 3 garderobes, a basement, battlements, ruins and a bailey surrounded by a relatively deep moat.

Let me know if you can think of any improvements or build ideas, especially if you have been to the castle (I was only able to build from pictures I found online).

Aerial photograph from: http://www.britainfromabove.org.uk/image/eaw005049?search=tattershall&ref=13

Please email me if you would like to use the castle on your server at: allminecraftbuilds@gmail.com 

To use the model, add the folder "Tattershall Castle" to the saves folder in .minecraft (under %appdata%/Roaming).