The more I compare all the shots, aerial and terrestrial,
the more I lean toward it being HVAC and/or Ventilation.

Yeah HVAC was my first thought.

Next to the unidentified tall appendage there are two smaller items -
they could compressed air tanks or something.

I'm still not convinced about the asymmetry of the structure - the
more I look, the more symmetrical the building looks.  The peak of the
buildings roof, is more or less in line with the center of the door
opening.   I'll check out the July 2007 aerial shots.