The Siegfried Line was a mammoth wall of German defenses that stretched from the Swiss border in the south to Aachen in the north, approximately 300 miles long and, in places, up to 20 miles deep. Built by Nazi Germany between 1936-38, over 500,000 workers were involved in its construction. This book gives a detailed historical background to the Siegfried Line, and a guide to what is left to see of it today.