Essays / Descriptive Essay on a historical building [4]

I am having a bit of difficulty writing a 350 word essay on a historical building in my town. It was once a fire station later converted into a museum, but it looks like a red barn to me. I wrote my paper once and my professor thought it was a good thought, but not a descriptive essay. Can anyone help me, I have to rewrite and resubmit to get a grade. Thanks