occupied territories, which was an especially complicated endeavor given the military situation. Nonetheless a concrete factory, a carpentry shop, a gravel sorting plant and further facilities had to be built. Besides these additional smaller bunkers intended to serve as air raid shelters were erected before construction on the main site began. For the transportation of material to and from the site the Reichsbahn laid down a network of siding that was connected to the Munich-Mühldorf line. Upon completion the entire bunker was to be covered with soil and planted over with trees and bushes, but considering the scale of the project it was hardly possible to effectively camouflage it from aerial reconnaissance during the construction process. Efforts to that effect were therefore not especially thorough. Indeed, the site was hard to miss, and the USAF took several aerial photos of it in February 1945 during reconnaissance prior to the bombardment of the airfield at Mettenheim and the train yard at Mühldorf. The site was discovered upon examination of the photos, as an overhead view of main bunker drawn in March 1945 and labeled "MUHLDORF (GERMANY) SEMI-BURIED INSTALLATION" attests. The site was never bombed, however. The reasons why are unclear. One reason could be that the existence of the work camp was known and that the Allies did not want to risk bombing it by accident. It may also have been known that its completion was unlikely and thus other targets presented a higher priority. Process The actual work on Weingut I began in July 1944. According to plans, the bunker would be made up of 12 arches stretching east to west in a barrel vault 400 meters long and 85 meters wide. The arches would have an internal height of 32.2 m, 19.2 m of which was under the ground level. Their thickness reached 3 meters, and would have eventually reached 5 meters through a further concrete pour. For the building of the bunker an effective and simple new procedure was employed. First an underground "extraction tunnel", fitted with a single train track and a gated roof, was built along the entire length of the planned bunker. Next the foundations for the abutments, which were up to 17 m thick, were dug. The gravel extracted from the foundations was piled up between the foundations to support the arches while they were being built, essentially serving as formwork instead of traditional