It's something I noticed more back when 2-sided media (tapes, records) were still competing with CDs in the marketplace. Tracklistings were traditionally structured that way, so hearing albums straight through was a new concept, for those whippersnappers out there. Regardless of what I'm listening to it on, The Fly is always "the beginning of side 2" of Achtung Baby.
That said, I'm not sure there's a better example than side 1 of the Joshua Tree. Sure, it's overexposed now, but there's a reason for that. It's probably the best five songs the band put together in their history. It's practically an album unto itself, with a beginning, middle, and end. It's the reason why the beginning Red Hill Mining Town is almost like, "oh, I forgot, there's ANOTHER side yet...."