That, exactly. Also note that (for City Hall) per Boston bylaw, knives under 2.5" are OK but not longer. (OK, a bit more than that will sometimes get a pass, but I wouldn't try it.) On the (relatively) bright side, I've been in there a zillion times with the pair of smallish knives I usually carry and the most they've done is hold them up to the mark on the side of the x-ray machine and hand them back to me with no comment at all.
Is it posted no firearms? It is not a federal facility, school nor post office...unless posted then I'd carry and see what they do. The worst case is to go home and pay on-line. Could be interesting!?!
I went there today, they do have a sign banning firearms unless your a cop with official business there. The knife policy is out the window. I had my klien electricians knife on me with a 1in blade, they didn't like it and said I had to lose it to come in. To avoid the walk back to my car I tossed it in the trash.