Stewart's "true" department store, referred to as the "Iron Palace", was built. This six-story building, with its cast-iron front, glass dome skylight and grand emporium, employed up to 2,000 people. The immense structure occupied a major portion of a city block near Grace Church, from Broadway and Ninth Street to Tenth Street and Astor Place. The establishment's nineteen departments included silks, dress goods, carpets, and toys.

By 1877 it had expanded to thirty departments, carrying a wide variety of items. As noted by The New York Times, "a man may fit up his house there down to the bedding, carpets and upholstery."