Beside a souvenir-ravaged stretch of Wall, the cellars are all that remain of the palace housing the Reich Security (SS) Office. The fascinating exhibition in the trench and the adjacent pavilion and park uses models, texts and photos to highlight the topography of the Third Reich police, military and security groups that were headquartered in this area, and discusses their organisation and the terror they cast across Europe. The most important lesson to take home is perhaps that these organisation only managed to thrive thanks to the continuous cooperation of many institutes and citizens. Set aside 2-3 hours to do it justice.