Well thanks very much - but to be clear I very rarely build, I paint, it's my mate (the actual layout owner who builds and yes it is a scratchbuild). There was actually very little for me to do on this being mostly glass.
However -I do know how it was done and is simpler than it looks. Each panel was drawn on CAD to make sure it all lines up and its basically lots of styrene I & L beams. The glazing designed to be slotted in and held in place with those black sections (Evergreen V groove cut into LOTS of individual pieces with a bit of microstrip at the top and bottom ends). The peculiar cage structure at the top again done on CAD and lots of styrene square rod of different sizes. The undercroft/carpark bit I know is brick sheets with individual bricks cut out to give that vented wall effect.
Sorry I know that doesn't go into huge detail. Its supposed to be based on the below, The John Moores Building now called the plaza, but only a small bit of it being so incredibly long.