So many elaborate and impressive buildings from the mid 19th to early 20th Centuries seem so anachronistic, being used for such otherwise mundane and utilitarian purposes such as train stations, post offices etc.

What was the need for such incredible effort, design features such as that enormous tower, and use of, one would assume, hard to procure and labor intense resources?

The scale of these structures also does not match the vastly smaller populations of those times. There seems to be a disconnect there somewhere.