The Monadnock Building, also known as Monadnock Block, is a historic proto-skyscraper in the Loop district of downtown Chicago, Illinois. It is arguably the world’s first skyscraper. The Monadnock is the tallest commercial building in the world with masonry load-bearing walls. It is located at 53 West Jackson Blvd.
The seventeen-story building stands 197 feet (60 meters) tall. The northern half was designed and built by Burnham & Root in 1889–1891; the southern half was designed and built by Holabird & Roche in 1891–1893. The building was designated a Chicago Landmark on November 14, 1973 and was also listed on the National Register of Historic Places.
The northern half of the Monadnock represents the last Chicago skyscraper built using load-bearing wall construction; in order for the structure to support its own weight, the walls at the base of the structure are six feet (1.83 m) thick. The building was so heavy that it sank into the ground after it was built, requiring steps to be installed at the entrances. The walls curve in slightly at the second story and flare out at the top of the building, lending it a form similar to that of an Egyptian pylon. Architect John Root’s initial plans for the building included additional Egyptian embellishment, but the developer insisted that the building have no ornament.
The southern half of the building was built using the more technologically advanced steel frame construction, which allowed narrower piers and wider windows. The radical difference in construction between the two halves marks the building’s place in architectural history at the end of one building tradition and the beginning of another.
The building’s name is taken from the New Hampshire mountain that gave its name to the geological term indicating a freestanding mountain surrounded by a plain.