I saw this outstanding, bee attracting plant outside Quebec city hall this summer and attempted to ask them directly with no response. I've been to several garden centers and nobody has been able to identify what this is. I can tell it's a type of veronica, but what varietal? Thank you!

Hard to tell the height from your pics but I wonder if it could be Veronicastrum (Culvers Root), maybe "Fascination."They are 3-5 feet tall and are related to Veronica.

I have both the native white variety and recently acquired Fascination; they are definately bee magnets.

Yes. True veronicas never have whorled leaves, where more than two leaves emerge at the same level on the stem. The plant in question has 5-6 leaves per whorl.

These plants were about 3-4' tall

Definitely Veronicastrum.
Next year they may be taller.