At the top of the building at the Southwest corner of the intersection of Milwaukee and Chicago Avenue in West Town reads BAER'S HALL 1887.
Although they were born three years apart, Louis (1846) and Solomon (1849) have the unique distinction of brothers that share the same birthday: May 14th. Born in Hoffstosten, Germany, they came to the US in 1867.
By 1875, both brothers had gone into the clothing business for themselves. Louis had partnered with David Leiser in a shop on North Avenue and Solomon (nicknamed "Sol") had partnered with Moses Maas on Clark Street.
All four gentlemen eventually combined forces and formed "Maas, Baer & Company," setting up shop in this new building, designed by Fredrick W. Aschlager, in 1887 and erected by August Eich, with a second location remaining on North Avenue.
Interestingly both brothers married into the Yondorfs, another prominent Chicago merchant family. Louis married Elizabeth Yondorf in 1878 and Solomon married Fannie Yondorf in 1879.
One thing that isn't clear is how Sol and Louis managed to just get only their names on this building (although one article referring to Eich from Industrial Chicago Vol. 1 (1891) refers to the building as The Maas & Baer's Hall). I'm guessing that they had the controlling interest in the construction of the building.
In 1899, Boston Store purchased major stock in the company. By 1910, the business was gone, although Yondorf Clothing remained there for at least another decade. Only two years later in 1912, Louis died at age 66. In 1928, Sol died at age 78. Both are buried at Rosehill Cemetery.