I have a picture of an individual obtained in Germany that was taken in the U.S. The back of the picture has the the name Mueller Bros., Photographers, 180 S. Broadway. The name of the city is not totally visible. At first I thought it was made in St. Louis, but the city directories there for the period from 1870 to 1900 did not list such a name. Upon closer examination I believe the city name is Baltimore. However, I don't have access to the city directories for Baltimore. I would appreciate any comments or information on this query. Thank you.