Bab al-Salam border crossing.
In 2012, images were taken showing Free Syria members at the Bab al-Salam crossing in Syria waving flags and pointing guns at a torn picture of Assad. Note the outside walls of the building, the floor pattern inside, and the courtyard windows. Roof top view clearly shows it was taken from the large building nearby the gate.
Jump forward to 2017, when the Bab al-Salam crossing was handed over to the Syrian Interim Government. A symbolic walk was taken from the gate to the same large building. Inside a ceremony took place in a certain room. Note the similarities to the No Name meeting room.
Satellite pictures of the building in question show something around the back that could be a set of stairs, or the sloped wall in the spiderweb picture… or not.
Everything else looks circumstantial enough to pin point the meeting place, but no smoking gun. Personally, if this is the building, I think any other pictures showing the spiderweb have already been scrubbed from the net.
And, in regards to Q asking about the buildings to the East of the spiderweb - that would be the refugee warehouses.
Total speculation, but they would be a perfect place to hide weapons, chemicals and other contraband. Red Crescent (Red Cross) and the UN are involved with this camp.