Of course it's illegal, you moron. And no, you have not looked in all sources.

First, to carry, you must have a CCP license from your county of residence.

Second, if you qualify for a CCP license, they give you a booklet telling you where you can, and cannot carry a concealed weapon.

Third, and the reason I knew you were a moron, common sense will tell you not to take a gun into a bank. Duh!

I think you will find it illegal to carry openly or consealed in any FEDERAL building any where in the USA. Most counties at this time have there own special rules as to where you can carry.Court houses and what ever. And Iowa for a sample allow any business to post a ( no fire arms )sign at their front entrance if the want.If violated it can be a criminal trespass charge just for doing so. Unless some thing else warrants stronger charge.Counties will vary while Iowa law makers are fine tuning its state CCW laws as we speak.