Looking up at the building, he looked back and forth between Donna and then stopped, his expression freezing in shock as he stared at her. That certainly wasn't a name or an idea he'd ever thought he'd hear. His expression softened a little and he lowered his gaze until he was staring at the ground with that same sorrowful look whenever someone had mentioned his home planet or the war.
Another split second, and he went back to himself, looking up at her, "Nahh! Why would I want a new one? I want my TARDIS." he scoffed and then looked back at the building's entrance, scowling a little and then shaking his head. "I wouldn't just abandon her..." he mumbled softly.