The Ontario Apartments were one of the first multifamily apartment buildings in Chicago catering to a middle- and upper-class clientele. The appearance of such a structure was novel in the then-semirural neighborhood of large houses in what is today the city’s River North neighborhood. Therefore, it was important that the structure conformed to the standards of fine houses, with brick and carved stone construction, decorative ironwork, and offered large apartments equipped with libraries, parlors, and servant rooms. The building was designed to be easily converted to a hotel, a change that was indeed made in 1893 to accommodate visitors to the World’s Columbian Exposition. Treat and Foltz had an active architectural practice in Chicago during the 1880s and 1890s, focusing largely on single-family residences in a range of styles. The large collection of drawings by the firm given to the Burnham Library represents an aspect of Chicago’s architectural history that otherwise would have likely been lost.