During the 9th and 10th centuries, fortifications (burhs) were constructed around towns to defend against Viking attacks. Almost no secular work remains above ground, although the Anglian Tower in York has been controversially dated to the seventh century. Recent evidence opens up the possibility that St George's Tower, Oxford, may be a surviving part of the defenses surrounding the Anglo-Saxon burh of Oxford. There is a reconstruction of an Anglo-Saxon settlement at West Stow, and contemporary illustrations of both secular and religious buildings are sometimes found in illuminated manuscripts.