"Amending this post to right a wrong. It wasn't Paul who mentioned the ceramic tile lining inside the tower, it was Dave H. who pointed out this very unusual feature."

Just a guess here but most of the tunnels thru mountains or under bays that I have been thru are also linned with white tile, and I am guessing that the tile is there because it reflects light quite well and helps give the best use of your light.

Sincerly, Thomas Edison