Try the new Grand Castle Generator, less controls and more unique results.
This customizer generates vartiations of fortresses, either random or controlled.
The formula is a perimiter wall with n sides, towers at each corner, turrets, and a main gate.
If you're new to the Customizer concept, start by hitting the "Open in Customizer" button on the right panel. After you play around with the settings and like what you see, click "Create Thing" to have it generated (takes a while) as an STL file you can download and print.
It is based on code from my previous castle generator at: http://www.thingiverse.com/thing:1612651
And both can be combined to create a castle with surrounding outer walls.
The structures are designed to enable printing without supports.
If you wish to enable details and enjoy a better preview, you probably want to download the code and open it in OpenSCAD.
Hope you enjoy!