The keep at Orford has been particularly extensively analysed in this regard, and although traditional explanations suggested that its unusual plan was the result of an experimental military design, more recent analysis concludes that the design was instead probably driven by political symbolism and the need for Henry to dominate the contested lands of East Anglia. The architecture would, for mid-12th century nobility, have summoned up images of King Arthur or Constantinople, then the idealised versions of royal and imperial power. Even formidable military designs such as that at Château Gaillard were built with political effect in mind. Gaillard was designed to reaffirm Angevin authority in a fiercely disputed conflict zone and the keep, although militarily impressive, contained only an anteroom and a royal audience chamber, and was built on soft chalk and without an internal well, both serious defects from a defensive perspective. During most of the medieval period, Iberia was divided between Christian and Islamic kingdoms, neither of which traditionally built keeps, instead building watchtowers or mural towers. By the 12th century, however, the influence of France and the various military orders was encouraging the development of square keeps in Christian castles across the region, and by the second half of the century this practice was spread across into the Islamic kingdoms. By contrast, the remainder of Europe saw stone towers being used in castles, but not in a way that fulfilled the range of functions seen in the western European keeps. In the Low Countries, it became popular for the local nobility to build stand-alone, square towers, but rarely as part of a wider castle. Similarly, square stone towers became popular in Venice, but these did not fulfil the same role as western keeps. In Germany, rectangular stone castles began to replace motte-and-bailey castles from the 12th century onwards. These designs included stone versions of the traditional Bergfriede, which still remained distinct from the domestic keeps used in more western parts of Europe, with the occasional notable exception, such as the large, residential Bergfried at Eltville Castle. Several designs for new castles emerged that made keeps unnecessary. One such design was the concentric approach, involving exterior walls guarded with towers, and perhaps supported by further, concentric layered defenses: thus castles such as Framlingham never had a central keep. Military factors may well have driven this development: R. Brown, for example, suggests that designs with a separate keep