Eisenmann was born in Germany in 1850 and emigrated to the United States some time before 1870, settling in New York City. At an early age, Eisenmann established a photography studio in the Bowery. A lower class area that was the hub of popular entertainment, the Bowery was known for its cheap photographic galleries and dime museums. Here Eisenmann discovered his clientele. Dime museums were modeled on P.T. Barnum's American Museum on Broadway which exhibited various human 'curiosities' as well as many unusual and questionable "scientific" exhibits. Similar in many respects to the circus sideshows, these museums featured human "freaks" who displayed their odd physiognomies and performed before gawking visitors. To help these performers market themselves, Eisenmann and his successor Frank Wendt supplied them with small photographs that they could sell or distribute to publicists. Precisely why Eisenmann was drawn to and focused on this peculiar clientele is not known, though there was evidently money to be made, as other photographers followed him into the business."