The funny faces behind the fence are put against the wall of the former Central Office for Statistics of the GDR. At the time it was mostly abanonded. There were always high flying plans to use this building or tear it down and replace it but nothing really happend. As of today the city owns the land and buildings and wants to build housing and cultural spaces. Considering the tight budgets I suspect it will stay this way for a while.
These throughways are quite common for socialist architecture. Many office and residential blocks were made on long rectangular shapes and to allow foot traffic they often installed these little throughways. Because the whole building was unsafe they tried to make it safer by adding some fencing above and around.
Nevertheless many people ignored the fences and used the giant facade to put up posters. These are most likely for a local theater piece. You can watch some urban exploration videos on Youtube if you like see more.