Always HCI (or Robotics) too. It's like, you never actually see what they're doing but it's always awesome (except for that large robot in some room on NS second floor right near the Wean bridge, but that might not be HCI). Also #proud :)
I think (?) the room on NS 2 you're thinking of is part of the Quality of Life Technology Center. <3 CMU and #proud. Can we all agree that the robot in the Gates 3 lounge area is somewhat creepy-looking though? His avatar looks like a cross between Julian Assange and Andy Warhol.