The Knox Hat Factory

I recently found out that at some point in the past hats were big enough to support a hat factory as big as the one above at the Brooklyn corner of St. Mark's and Grand Avenue (today's Prospect Heights). That's a lot of hats. Built in 1890, it was purported to be the largest hat factory in the world, and they made every conceivable type of headgear here, from top hats to straw boaters to policemen's helmets.

As this site attests, the building still exists, though it's been beheaded.