The building was one of the first five selected by the Chicago Commission on Architectural Landmarks in 1958, "in recognition of its original design and its historical interest as the highest wall-bearing structure in Chicago". The commission went on to note that the "restrained use of brick, soaring massive walls, omission of ornamental forms, unite in a building simple yet majestic." In 1973, the Chicago City Council voted unanimously to designate the Monadnock a Chicago Landmark, stating that "The two halves of this building provide a unique perspective for examining the history and development of modern architecture. ... Together, they mark the end of one building tradition and the beginning of another." Critics of the Monadnock's landmark status objected that it would prevent the necessary demolition of the building, which was "an excellent example of a building that is ... no longer fulfilling the functions it was designed to fulfill" and "a wasting asset" that underperformed the market and was far less valuable than the land on which it stood would be.