There is a bit of unused dialogue found in the Final Fantasy VII game data that would have taken place outside the Shinra Headquarters, before the party head in for the first time, and in the elevator, if the player entered the building through the main entrance. Outside the building, Barret would suggest that Cloud knows the place well, to which Cloud would have answered it to be his first time there. Barret would then have said he has been at the headquarters before, back when he still had both his hands. The elevator scene is similar, with Cloud saying he's never been to the place before and asking if Barret is familiar with it, which would have prompted the same response from Barret. These bits were cut off the final game and nothing in the finished version suggests Barret would have ever visited the Shinra Headquarters before.
Contributed by GladiatorGr