The Monadnock was commissioned by Boston real estate developers Peter and Shepherd Brooks in the building boom following the Depression of 1873–79. The Brooks family, which had amassed a fortune in the shipping insurance business and had been investing in Chicago real estate since 1863, had retained Chicago property manager Owen F. Aldis to manage the construction of the seven-story Grannis Block on Dearborn Street in 1880. It was Aldis, one of two men Louis Sullivan credited with being "responsible for the modern office building", who convinced investors such as the Brooks brothers to build new skyscrapers in Chicago. By the end of the century, Aldis would create over of new office space and manage nearly one fifth of the office space in the Loop.