The idea for the walk came from Patrick, who had sent me a copy of his map. It showed the route of the old customs wall of Berlin, a fifteen kilometre circle that until 1861 was the limit of the city. There is nearly nothing remaining of the old wall today – just a set of foundations not far from Anhalter Bahnhof and – of course – the Brandenburg Gate, but it lives on in other ways. The route of the U-Bahn line through Kreuzberg for instance and the stations along the way; Kottbusser Tor, Hallesches Tor, Schlesisches Tor… the gates are no more but they live on in these names.
Patrick had walked the route of the old customs wall before and invited me to join him as he did it again. Along the way we would see, as our footsteps followed the path of the invisible wall, how it shaped the development of the city and how you can still see its influence more than 150 years after the city broke through its limitations to become the Weltstadt of the early twentieth century, its population swelling to a number that the old wall could never have contained.










