One of my mom's guesses (she worked in the building where JB Hudson's was located, so I thought she'd have it for sure, but Chris, my friend from Boston's correct answer was even more surprising!) was the Foshay Tower.
Andrew had a tour of the tower and got to go up to the observation deck a few weeks back for a homeschool coop outing. I did not attend and wish I had, as the building is a fascinating and beautiful one.
The iron work inside of the Foshay Tower is famous, and it was worked at the same company as the gate at JB Hudson.
The Foshay was designed to look like the Washington Monument, and contains four bronze busts of George Washington in its interior.
Nowadays it is a tres chic hotel, which I want to mention because some of the photos above are from their site. For those with some K left during this recession, it would be an awesome place to stay a night, and you'd be right in the heart of downtown Minneapolis, which is a lovely place to visit.