We found 1 window (I'll have to double check, but this building is between C and D checkpoints). The windows doesn't meet the wall on the top, there is a little gap.

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=357763845

We also found that when at the top of the stairs a checkpoint C, the bots can shoot through the wall killing the defender. If you walk up the stairs it's the right wall once you get to the top. Our guys sitting in the area to defend the door opposite the stairs gets shot most times from the other side of the wall.