There were a lot of Nazi sympathizers in that area. Could the reason for the guards and dogs be that this was actually a bunker? Many of the old German families in the area there were loyal to Nazi Germany, and believed that Germany would prevail in the war, while at the same time, being prominent families, had to keep these beliefs secret. Check out the history of Federal Hill, and or Lake Valhalla, lots of stashes and caves have been found over the years.