germans black program

in ww2 germany was a leader in weapon technology and it was no accident. long before the end of the war, german army was looking for alien technology. in the heart of germany they found something. nobody knows any details, but near the village "kahla" they have found something. the area around this village is called Thuringian forest, with high mountains, deep valleys, and a very small population. near "kahla" they tunneled a whole mountain called "walpersberg". inside they developed a huge facility, and the the most futuristic plane of world war two was build. on top of the mountain was a runway. you could say now, that it was only a plan factory. that`s right, but why there are a lot of ufo sightings and why the german army still uses this area? it is a restricted area.