Hi, railsquid here. These pictures were taken in the Eberswalder Straße in the Prenzlauer Berg district, somewhat to the north of Friedrichstraße. The elevated railway line in the background is former U-Bahn line A, now the U2, running along the Schönhauser Allee; Dimitroffstraße station (now Eberswalder Straße) is just to the left, though not visible. The former Dimitroffstraße itself, now Danziger Straße is the continuation of the Eberswalder Straße on the other side of the U-Bahn line. There are also trams running on the Schönhauser Allee parallel to the U-Bahn line, at least one route (I forget the old numbers...) would have run through to Friedrichstraße, although at the time the trams were routed around the back streets to the east of the station and changing there wasn't very convenient.
If the photographer had turned round and marched down the Eberswalder Straße to the west, he would have found the Berlin Wall blocking his path, and the trams terminating shortly before it. The tram line has been since extended to the west, along what is effectively Berlin's inner ring road, and is currently being extended to the new Hauptbahnhof. The old turning loop is still there and in occasional use.
I know this because I lived in the immediate area for many years from about 1991 and spend some time in the area last month
Dussmann.