How is this still not a thing? I know it will probably tend to be spamy, but all completed constructions could be grouped into one notification to show the list. Some things take time to build, and I'd like to get notified when I plan few steps ahead and steadily execute my plans. If anything enable it as gameplay option.

Agreed 

Bump! Loving the game so far but this is something that feels sorely missing.

It would really add to the level of accomplishment knowing when the building you've been working on for ages is finally completed in your city :D

As OP says it could easily be grouped up like other notifications are so that it doesn't become spammy!