Martin's "Castles" - The Red Keep

The Red Keep, as seen in HBO's Game of Thrones

An example of a 14^th century fortified manor house. Note the crenellated battlements; contemporaneously, these would have contributed to the owner's identity as an aristocrat, when aristocrat was still synonymous with soldier.

The Red Keep is too fantastic to be considered a castle proper. It seems more akin to a palace with the ascetic features of a castle, such as towers and crenelated battlements. The castle imagery may be a deliberate choice in the fictional context – the Targaryen builders may have sought to overawe their subjects to discourage disloyalty, rather than simply trusting in the military strength of their fortifications.

A building that looks more military focussed than it really is (often by the simple inclusion of crenellated battlements) serves to reinforce the identity of the castle owner as a military figure. In this way, the Red Keep shares some commonality with the fortified manor houses and other late medieval transitions - their image reinforced a military or lordly identity, but they were not a primarily defensive structure in the same way that castles were.

I believe that Martin deliberately evokes the castle imagery as part of his larger world construction: peppering his fictional world with “castles” - a real, explicitly medieval structure - serves to inject a sense of “realness” and “medieval-ness” into his fantasy works.