The Medieval castle has always caught the imagination and its demise as an active military concept was a result of the development of heavier guns that increased the chances of rapidly surrounding and defeating its inhabitants. The result was imposing structures that saw service as prisons and administration centres, before becoming interesting artefacts to be examined by tourists. This may explain why subsequent updated versions of the technology were produced into modern times but largely overlooked. This book is another volume in an excellent series that uncovers the history of these fortifications, in this volume looking carefully at the fortifications of three neutral countries during the 19th and 20th Centuries. It is very well illustrated throughout and its authors once more present an authoritative history that is unlikely to be equalled and never to be beaten by any other account of the subjects.