I'm always amazed when I find a slice of Brisbane that I've been walking past for years. Miller Park runs between William Street and Queens Wharf Road, both streets I would walk at least part of the way down each week. I think the fact that the park is next to the Commissariat Stores means your attention is drawn to this old building, but the park is a neat bit of greenery in the midst of the city.
I can't find much information about it, but suspect it was named after Lieut. Henry Miller who along with John Oxley set up the convict settlement of Redcliffe.