The Ponttor is one of the two remaining gates of the outer Aachen city wall; the other gate is the Marschiertor.

It was completed around the year 1320, when the city grew beyond the borders of the inner city wall. The name of the gate came from the nearby city area "Pontviertel", which again is based on the Latin word pons (bridge).

Today it is used by the German Scout Association Saint George (DPSG).

source:

https://de.wikipedia.org/wiki/Ponttor

https://en.wikipedia.org/wiki/Ponttor

http://www.dpsg-heilig-kreuz.de/DPSG_Stamm_Heilig_Kreuz/Ponttor.html