The Monadnock Building: Where the Brick Wall Ran Out of Room

The Monadnock Building stands at 53 West Jackson Boulevard, filling the block between Jackson and Van Buren on the west side of Dearborn Street. Sixteen stories of dark purple-brown brick, no exterior ornament beyond the swelling base and the slight outward flare at the cornice. From the street it reads as a single severe slab. It is not. It is two buildings, joined at the hip, two years apart in construction, designed by two different firms for the same client. Walk the length of the façade and you are walking across the moment in 1891 to 1893 when load-bearing masonry construction ended and the steel-frame skyscraper began.

The transition is legible in the wall.

The north half, 1891

The north half was designed by Burnham and Root, the most influential commercial-architecture firm in Chicago in the 1880s. The client was the Brookline real-estate investor Peter and Shepherd Brooks, who had asked for a building that would be efficient, durable, and as nearly devoid of ornament as the period allowed. John Wellborn Root, the design partner, produced a façade that has almost no historicist reference. The base swells slightly outward, the cornice flares slightly outward, the wall in between is uninterrupted brick. It looks, to a twenty-first-century eye, almost modernist. To an 1891 eye it looked stark.

The structural system was load-bearing masonry. That meant the exterior walls carried the entire vertical load of the building. There was no steel skeleton. There was no concrete frame. The brick wall was the structure. Floors framed into it, columns inside helped, but the wall held the building up.

Walk to the entrance and look into the door reveal where the wall is exposed in cross section. The exterior wall at the base is six feet thick. Six feet of solid brick, tapering as it rises, reaching about eighteen inches at the top of the sixteenth story. That taper is not a stylistic gesture. It is what the structural calculation requires. At each floor, the wall has to carry the weight of every floor above it. The higher you go, the less load, the thinner the wall can be.

The total height was 215 feet. Sixteen stories. The architectural record states the case plainly: this was the highest economically viable for a load-bearing wall design. Go taller and the wall thickness at the base would consume the rentable floor area on the lower floors. The math turned over. A seventeen-story brick building's ground floor would be a fortress, and fortresses do not rent.

The north half of the Monadnock is the tallest load-bearing brick commercial building ever constructed. Not the tallest in Chicago. The tallest anywhere. The ceiling.

The south half, 1893

Two years later, the Brooks brothers commissioned the southern half of the building on the adjacent lot. Same address. Same project. Different architects: Holabird and Roche, the firm that would soon build the Marquette Building one block away. And, critically, a different structural system.

The south half used a steel skeleton. The exterior walls of the south half are still brick. But the brick walls do not carry the building. The steel frame inside does. The wall has become a curtain, a cladding, a weather barrier. It holds itself up, more or less, with help from the frame. It does not hold the building up.

The consequence shows in the floor plates. The south half achieved roughly fifteen percent more rentable floor area on the same lot footprint, at roughly fifteen percent less construction cost. The wall stopped eating the floor.

Walk the length of the building along Dearborn and look closely at the brick. The two halves match almost perfectly. Same dark purple-brown Roman brick, same slightly swelling profile, same minimal ornament. The Brooks brothers and Holabird and Roche made the visual decision to extend Root's elevation across the addition. They did not announce the structural shift with a stylistic break. The shift is invisible to the casual passer-by.

But the floor plates know. The interior knows. And once you know, the wall stops looking the same.

Why this matters

In the architectural history of the skyscraper, the Monadnock Building is usually a footnote next to the Reliance, the Sullivan Center, the Auditorium, the Home Insurance Building. The buildings that are credited as inventing the skyscraper are the buildings that built the new system. The Monadnock is the building that ended the old one.

That is the unusual role. Most great buildings in a technical transition are the first to show the new thing. The Monadnock is the last to show the old thing, at the moment the old thing has been pushed past its economic ceiling and is replaced, in the same project, on the same lot, with the new thing.

What this means for an architect or an engineer reading the building is this: the Monadnock is the only building in the world where you can read load-bearing masonry construction at its absolute maximum, and then walk fifty feet south and read the steel skeleton construction that replaced it, in walls that look almost identical from the outside. The structural revolution is staged in one address.

For Chicago, that was the argument. The First Chicago School was the working out, between 1885 and 1900, of which structural system would carry the modern commercial building. The Monadnock is the proof in the floor plates. Six feet of brick at the base cannot rent above a certain height. A steel skeleton can rise indefinitely. The new grammar had to win because the old grammar had nowhere left to go.

What to look for

Stand on the north side of Jackson Boulevard, looking south at the Monadnock's north elevation. Count sixteen stories. Notice the slight outward swell at the base, the slight outward flare at the cornice, and the almost complete absence of ornament between. Notice the regular vertical rhythm of the bay windows. The bays are projecting oriels, which the Brooks brothers wanted for additional light and floor area; they are also there because in a load-bearing wall, every notch reduces the wall load by reducing the wall area, and every projecting bay extends the rentable floor without extending the heavy ground-floor wall footprint. The bay windows are an economic solution as much as an aesthetic one.

Walk to the main entrance on Jackson. Look into the door reveal at the side of the doorway. The six-foot wall thickness is visible there in cross section. Stand close. Put your hand against the brick. The wall is thicker than your arm is long.

Now walk south along Dearborn the length of the building. The shift from the 1891 north half to the 1893 south half happens at a small expansion joint about midway along the elevation. You can see it if you know to look. The brick coursing changes slightly. The window proportions shift by a few inches. The cornice line continues unbroken.

Look up at the south half. The wall looks like the north half. It is not. The wall is decorative cladding on a steel frame. If the same wall were forced to carry the same load on this footprint, sixteen stories would be the absolute ceiling, and the rentable floor area would be unworkable.

The building is the question and the answer in one elevation. The next century of tall buildings everywhere in the world is the consequence of the answer settling here, in 1893, between Jackson and Van Buren.