The site is on top of the roof of the student residence at Halbauer Weg 19/21.
Seen from the north at Kamenzer Damm:
The student residence seen from the south-east. On the roof there are some old and offline o2 antennas, seen on the left mast of the upper picture as well as below on both left masts:
Some Telekom sector panels seen from the west: