castellate

from The Century Dictionary.

• noun A lordship or castellany.
• To give a castle-like form or appearance to; furnish with turrets and battlements in the manner of a castle.
• To assume castle-like forms, as moving clouds.
• Same as castellated.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To build in the form of a castle; to add battlements to an existing building