The "Katzenkopf" (1937 – 1939) was the second largest and northernmost positioned fort of its kind and is today the one still visible of the entire-line. In its preserved interior parts it hosts the "Westwallmuseum" with an interesting collection of World War II weapons and photos.
For the "protection of its territory", Germany started in the year 1936 (officially in 1938) the "construction of an enormous fortified line" along its western borders. This line reached from the border-area of Basel (Switzerland) up to Kleve (Germany, lower Rhine area) and was 630 km long. They called it the "Westwall".