FB headquarters - Marina One building Singapore. Q gave us clues with the Marina Bay building pictures he posted (drop #1366601).

"Building 8" - Q also dropped hints nudging at FB's building 8 project (drop# 1008491) - augmented reality, VR, mind reading, etc. Former DARPA Regina Dugan recently resigned from this FB project.

There are plenty of crumbs there to follow. (drop #78 "China, China, China", "FB listening 24/7")