"In their Monadnock Building,... Burnham and Root reduced the building to an elemental statement. Finished after a hiatus of several years, the building was stipulated by the Brooks brothers to be of traditional bearing wall construction, with an unprecedented height of sixteen stories. Root therefore faced a problem of harmonious expression of this height. His original idea was an ideogram of the Egyptian papyrus column, but over the long period of design he gradually stripped away historical detail, leaving only a massive brick pile with a slightly curved base and outward curving cavetto cornice at the top. No stringcourse or projection breaks the continuity of line so that the tapered mass of the Monadnock Building becomes its own ornament. In spite of Root's artistic achievement in making the tall building a unified, coherent statement, it was structurally traditional, employing cast iron and wrought iron framing only for window spandrels and the internal frame. Consequently the walls at ground level had to be six feet thick to carry the upper floors; this massive bulk then rested on an immense iron and reinforced concrete raft.

— Leland M. Roth. A Concise History of American Architecture. p176.