With the alpha shader at the end of the decal texture we can adjust them seamless with other buildings:  

Hello! thanks for your reference, i belive you are talking about Wall's tower's this one is the defense or the scout tower wich is more gameplay-wise oriented. Theather:  

Hey, I don't know how realistic would you like Ancient Greek towers to be, or how many variants could be done, but here I described how they were according to their function:    And here a couple of images from the book I mentioned: Basically, if the upper chamber had catapults, the roof was gabled, and the slits wider, with double-leafed outward-opening side-swinging shutters attached to the outside. Otherwise, if it also had archers, then it had an open fighting platform protected by a parapet at roof level, similar to the right tower of the lower picture. Cilindrical versions were harder to build but more resistant.

New variant:  

Update: Added dirtier version of houses, storehouse, sentry, defense and forge: House: Storehouse: Forge: Sentry and Defense: