BG Tower has some details added.

BG Tower needed a few items to complete it, such as the staircase.  Scratch building a staircase in 1:450 scale was a daunting idea, so I turned to our ship-modeling friends for some help.  Gold Medal Models (outstanding products!) makes a detail set for the USS Arizona in 1:429 scale that includes several detail parts that will work in T, among them several stairways. These aren't -exactly- what I wanted being based on an all-steel prototype, but close enough and good for effect.  

Above you see the length of stairway and a platform.  The prototype rests on a couple wood beams;  I found some scrap brass to create these.  Note: on the final model I installed "X" braces made of thin styrene.  If I was smart I would've installed them at this stage.  I added them later.

Some very finicky work with super glue and all was installed. 

I also needed a smoke jack;  The construction drawings call for a masonry chimney, but BG actually just has a steel tube flue.  I used a cut-off shaft from a thumb tack, and a small bit of brass shaped with a ball-point pen to be somewhat concave ACC'd on top.  The figure is part of a 1:450 Queen Elizabeth 2 sailor set, repainted into blue from his dress whites.

When installed, the ground level will go up to the top of the white foundation.