Apple is reportedly expanding it's Head Quarters in Cupertino, it has taken up old abandoned HP buildings in the area, and in some areas is even knocking down older structures in order to erect new ones.
The buildings that Apple has taken over from HP still have the HP logo in places, and the addresses on signs written in HP's style. But in most cases you can clearly see the over-painted Apple Logo on the majority of HP's old signage.
Because of Apple being based in Cupertino for the last three decades Steve jobs is reluctant to move out of the area, and as such this is why these old HP buildings have been acquired.