In the sequence set to the Blue Danube Waltz, we see a Pan Am orbital shuttle docking with a partially-completed space station. Here is a clip from that sequence on YouTube. There are good views of the space station at 0:02-0:28 and 1:28-1:46 in that clip that keep the camera at a respectful distance, as would be expected given late 1960s technology: models (since no CGI yet) and large cameras guided on rails (no motion control, either). But the final shot (1:56-2:17) has the camera viewpoint go through the structure of the space station! How was this accomplished? Was the model the size of a house, or did Kubrick have something else up his sleeve?
At first I thought it might have been a breakaway model, used by the likes of Orsen Welles to make a camera appear to pass through a neon sign or window in Citizen Kane, but then I watched the clip and realized this could not be the case.
I have had some experience with motion control cameras, and this certainly seems to have been produced using a track system and large model. Some further digging revealed that the studio model was approximately 8 feet in diameter, which accounts for the astonishing level of detail and the fact that a camera can pass right through it.