One of the small towns I grew up in had a post office, probably built in the early 20th century or very late 19th (I don't recall for sure, but I'm certain it had the date displayed on one or more floor or wall plaques, somewhere)
Heavy metal doors with perfectly smooth-operating hinges. Marble everywhere—floors, counters, stairs, [edit: hell, even the walls!], everywhere, and this was not in an area that mined marble, it was surely imported from at least several hundred miles away, and likely much farther. Thick, ornate brass doors on the PO Boxes. Serious- and heavy-looking metal light fixtures. I loved going there as a kid. It seems silly, maybe, but that post office felt magical.
Similar story for older libraries (including the one in that same town), older university buildings (ditto), older bank buildings even. They're all so nice to be in, and embody a confidence in some kind of permanence and continuity.
Now all that shit's in strip malls or buildings that are otherwise intended to have a 50-year lifespan at most. Cheap low-pile carpet on plywood, comically fake ornamentation if they bother to have any at all.
What's so weird is that we built basic public buildings like we were rich, back when we were, relatively speaking, paupers, but now that we're wildly rich we build everything like we're paupers. It'd be inconceivable for anyone to get half the budget it'd take to build a post office like that one, for a new post office building these days.
Hell, even my Grandparents' cheap, small post-WWII house in a cheap rural town had details that are rarely found outside luxury homes today—the heavy solid-wood front door and extremely solid-and-smooth-feeling metal doorknob, nice metal switch-plates and heavy-feeling, satisfying switches, that kind of thing. I bet you'd have to special-order a storm door to get one with more than half the metal in it that theirs had and it'd cost a fortune, and god, all that stuff felt so nice, and held up to years and years of use without being the worse for it. Their whole working-class neighborhood was built like that.