Back of the Pantheon - Rome
This is perhaps the most recognizable building in the world, but you only see photos of it from the front. Walk around to the back and another story is told. The front is clad in stone, but the rear has exposed brick. I'm not sure how this looked when it was originally built, but if there was stone here originally, it is now gone.
August 3, 2011 Update:
I was looking at some of my other photos I took of the Pantheon and I clearly see remnants of old stone cladding over the brick which is now mostly gone.
Front of Pantheon - Rome
The Pantheon is the oldest building in Rome that has been in continuous use for 2,000 years. Click the photo for a link to a website describing the history of the building.
Bill Graham Civic Auditorium - San Francisco
The idea of saving money on the backside of the house isn't a new one. Here in San Francisco if you stand in the middle of Civic Center Plaza, all you can see are granite clad buildings.
On the south side of the plaza sits Bill Graham Auditorium. Built in the 1920's by architects John Galen Howard, Frederick Meyer, and John Reid, Jr., it fills out one side of the plaza with historic classicism. Walk around the building, however and you will see the building clad only in brick.
The back of the building is quite visible as you cross Market Street, so the decision to clad it in brick rather than granite was probably to save money. They turned the granite around the corner just enough to maintain the view from the plaza.