This article addresses the depth of our knowledge regarding Viking fortifications in England, Scotland, and Wales, assessing perceptions of them as a monument type. This sudy includes the investigation of antiquarian influences upon the interpretation of these sites. It is suggested that archaeological knowledge of these monuments is largely fragmentary, and that in some cases, current understanding can in fact be based on interpretations dating back as far as the 17^th or even 16^th century. Additionally, it is proposed that Viking fortified sites do not exist with any form of homogeneity as a monument type. The research process of these investigations, findings, and two case studies are summarized. The article discusses the current state of knowledge regarding Viking fortifications and suggests how the study of them should proceed.