Coming from Maastricht, the medieval Grendelpoort used to be the only access to the old centre. All traffic had to pass through it. In May 1940, the German army entered through the narrow gate in the direction of Maastricht, and in September 1944, troops and tanks of the American Old Hickory Division did the same in the opposite direction. Everything only just fitted in.
Not long before that, pupils of the SS-Reichsschule, an elite school for future Nazi leaders, marched through the same gate while making music, after they had taken a Sunday walk in Valkenburg.