Broadly speaking, most rocket systems appear to have at least 3 or 4 fold radial symmetry about their long axis (if you don't consider internals or smaller features not obvious from a distance). A notable exception is the Space Shuttle, which (broadly) displays only bilateral symmetry.
Descriptions of launch profiles often include roll and pitch maneuvers. For the shuttle, it's quite obvious what is going on. Not so much for a vehicle like Apollo.
Presumably, for vehicles such as Apollo, Gemini, and Mercury, pitch, roll, and yaw axes were consistent with the crew's seated positions (or vice versa) - "pitch down" equated to the crew experiencing a "forward" rotation.
When sitting on the pad, in which directions were Apollo's pitch and yaw axes oriented relative to the launch tower? What visual cues did the vehicle have purposely or incidentally that one could use once the vehicle was in flight to discern its orientation about the roll axis relative to the viewer?