Below is link to a photo on U of M's early Detroit images site of the Cadillac Hotel from what I would guess is sometime around 1900. The picture was definitely taken after 1896, since the Majestic Building at Michigan and Woodward can be seen clearly in the background. The hotel is the large white building on the left, which was renamed the Book Cadillac when it was bought by the Book family in 1917. It was torn down and replaced on the same site by the current Book Cadillac Hotel in 1923.

Picture of Cadillac Hotel:
http://quod.lib.umich.edu/cgi/i/imag...5DEB02E629.TIF

You can't see much of the building across the street from the hotel, but if you look at the roof of that building you can see a partially obscured sign that most likely says "Laundry." It appears that Banner once occupied at least part that building. The address given for Banner in the 1893-94 city directory is 73 Michigan Ave,, but the address for the main entrance to that building would have been 71 Michigan. So, there may possibly have been a mistake in the document you read.

Here is that directory listing:
http://distantcousin.com/directories...?Pages=118.jpg

73 Michigan is the same part of that building that's occupied by the Gately's store by the time of the Shorpy picture [[supposedly 1906). By then it appears that Banner had moved to just a small street-level office in the adjacent building at 83 Michigan. I don't know when exactly, but I do know that at some point they moved their plant to a location at Brooklyn and Plum near Tiger Stadium, because my grandfather knew some of their drivers and we used to park there for ballgames. They were there into the 1980s.

Here is the earlier DY thread on the Shorpy picture:
http://detroityes.com/mb/showthread.php?t=4759

You should keep in mind that none of the old addresses will correspond to current addresses. The city underwent a comprehensive addressing reform in the 1920s that changed all of them.