A conversion of the Griffon Fortress tileset (link is external) already converted for Skyrim (link is external). Currently have the tower pieces done, though they don't have proper textures assigned. Atrayonis played around with one of these, hence the Old Ebonheart screenshot.
The original resource states these may be freely used in other mods.
Added the wall pieces – don’t know whether the two textures are completely new or modified vanilla ones, but in either case they’d need to be replaced anyway (to fit Morrowind’s) and serve only to show how the walls are suppose to look like)