The Fifth Desk · Evaluation
Act I · The Map
Bruce Graham and Fazlur Khan (Skidmore, Owings and Merrill) · a mixed-use tower of a hundred storeys, scored as the tower as it stands: the braced steel tube with its taper, its black skin, its stacked uses and the masts on its roof, with what has been built onto it in its life as that work, the remodelled plaza at its foot and the observatory’s later fittings among it · a steel frame tube braced on every face by great diagonals that cross the full width of each face through many storeys at a time, the diagonals, the corner columns and the horizontal ties meeting at visible nodes · a rectangular plan whose sides draw in steadily from base to top, a truncated tapering prism · black anodised aluminium on the structure, bronze tinted glass, the diagonals expressed outside the skin line in the same black · shops and parking at the foot, offices above them, a sky lobby with shared amenities, apartments above it, the observatory and the floors above it near the top, and two masts on the roof · the roof at about 1,128 ft (344 m) · 875 North Michigan Avenue, Chicago · designed from 1965, built 1965 to 1969, occupied from about 1969 to 1970 · Skidmore, Owings and Merrill, Chicago office, with Bruce Graham as design partner and Fazlur Khan as structural engineer · as it stands, in use in its original kinds, the plaza at its foot rebuilt in the 1990s
Mode
The braced tube as building; a mixed-use tower in which the structure against the wind is the face, and shops, parking, offices, a sky lobby, apartments and an observatory share one shaft
Mythos
The truncated obelisk, the stele rooted and enduring; a frame laced and bound against the elements like a rigged mast or a trussed bridge stood upright; a whole town in one shaft
Phase
Designed from 1965; built 1965 to 1969; occupied from about 1969 to 1970; the plaza at its foot rebuilt in the 1990s; in use in its original kinds for about fifty-seven years at this reading
Presentation
A tapering rectangular steel tube braced by diagonals across every face; black anodised aluminium and bronze tinted glass; uses stacked from the street to the observatory; two masts on the roof
Register
Severe, black and cold; the dread of weight held in the air, made legible from the lake shore and the length of Michigan Avenue; less moving at the foot
Scale
One tower holding a town’s uses: the household, labour and commerce, the city’s traffic, and the wind off the lake
Governing Proposition
A firm and its engineer take the steel and glass prism of their city, which hid its structure behind a regular wall and kept its uses in separate towers, and turn it outward: the bracing becomes the face, the prism tapers, and a hundred storeys of shops, parking, offices and homes are stacked in one shaft. The wager of the building is that structure honestly shown can carry a whole vertical town at a reasonable cost and be its image too; its limit is that what it shows is how people may be stacked, not what the stacking means to them.
Act II · The Essay
Movement I
The John Hancock Center stands at 875 North Michigan Avenue in Chicago. It was designed from 1965 by the Chicago office of Skidmore, Owings and Merrill, with Bruce Graham as design partner and Fazlur Khan as structural engineer, built from 1965 to 1969, and occupied from about 1969 to 1970. It has a hundred storeys, and its roof stands at about 1,128 ft (344 m), with two masts above it.
The work scored is the tower as it stands: the braced steel tube with its taper, its black skin, its stacked uses and its masts, and what has been built onto it in its life as that work, the remodelled plaza at its foot and the observatory’s later fittings among it. The design is one, and it is credited to the architect and the engineer together: the taper, the skin and the stacking are as much the work as the diagonals, and collaboration is not charged. The neighbouring Water Tower and the rest of Michigan Avenue are its context.
The tradition it inherited in Chicago was the steel and glass prism: a tower of constant section, its structure hidden behind a regular curtain wall and shown only by applied mullions, its uses kept apart in single-purpose towers. The Seagram Building (8.5) in New York, the prism at its most refined, stands level with the Hancock or above it on every axis. The Hancock did not refine the prism. It took the structure out of hiding, broke the constant section and put a whole town’s uses into one shaft.
Movement II
The structure is a steel frame tube braced on every face by great diagonals. Each diagonal crosses the full width of its face and runs through many storeys at a time, and the diagonals, the corner columns and the horizontal ties meet at visible nodes. The frame is proportioned so that each face, and the four faces together, act as one tube against the wind, the nodes carrying the forces round the building. At this height the wind is the load that governs, and the diagonals are the cheapest way to make the outer frame act as one; the economy of the building rests on them.
The tower is a cantilever from the ground against the wind, and it shows it. The diagonals are expressed outside the skin line, in the same black as the anodised aluminium that covers the frame, and the bronze tinted glass lies between them. The black skin is drawn tight over the structure, so that the frame reads clean and the structure and the image are one. From Michigan Avenue the force the tower stands against is drawn across its faces at the scale of the city, and anyone passing can see how it stands.
With Khan’s other tube systems, the framed tube before it and the bundled tube after it, the braced tube changed what height cost. The tube systems became standard knowledge of supertall structure, and expressed diagonal bracing recurs on the faces of towers across the world from the later 1970s. Among the posted towers of the same firm, the Burj Khalifa (7.8), whose buttressed core comes after the tube systems in the same line of thought, stands below the Hancock on every axis but The Archetypal Deep, where the two are level.
Movement III
The plan is a rectangle whose sides draw in steadily from base to top, so that the tower is a truncated tapering prism, an obelisk without a point. Its floors are largest at the foot and smallest at the top, and the taper is the stack of uses read in section. The deep floors at the foot suit shops, parking and offices; the shallower floors above suit apartments, whose rooms need daylight within a few metres; the narrowing top suits the observatory and the masts. Take away the taper and the stack loses its fit, and the tower would read as a slab with no reason in its shape.
The taper does structural work too, drawing the mass in toward the top and stiffening the tower against the wind, and it is resolved so that the diagonals stay true on faces that narrow as they rise. The taper and the X are one law. The same diagonals cross the parking floors and the apartments, and the same taper that widens the base for cars narrows the top for the view. Car, shop, desk, home and view are all held under it. Only the masts set a second law on the first, the broadcaster’s, and they are resolved more roughly than the rest.
The taper also makes the tower seem taller than it is and gives it the sloped stance of a mountain or a pylon. From the lake shore and the length of Michigan Avenue the black mass carries a severe grandeur, the dread of weight held in the air. It reads as rooted and enduring, a stele rather than a box stood on end, and the diagonals bind it like a rigged mast or a trussed bridge stood upright. But the plan gathers nothing: there is no threshold, centre or sacred interior where the whole is met, and the myth is evoked by the form and only partly built.
Movement IV
From the street up, the tower holds shops and parking, offices above them, a sky lobby with shared amenities, apartments above that, the observatory near the top and the masts on the roof. A person can be housed, employed, fed, parked and served in one structure. The sky lobby is the street lifted into the air; the shared amenities halfway up and the parking inside the building make a resident’s day vertical in a way that separate towers could not. The building made the vertical city a way of living, and it has been lived for half a century.
That is the tower’s disclosure, and its limit. It shows how people may be stacked, and says little of what the stacking does to them. Inside the floors the form is less felt than outside: an office or an apartment here is lived much as one elsewhere, save for the view and, at some windows, a great diagonal crossing the glass, where the structure’s necessity becomes a cost to the life the floor was built for. The Unité d’Habitation (8.6), which holds dwelling more deeply, stands above it on The Unconcealment and The Encompassed, and on Pressure on Tradition.
The views from the upper floors over the lake and the grid are a sublime of their own, but they belong to the site and to any tower tall enough; they are credited only as far as the narrow top and the observatory frame them. At the foot the building is less moving. The street level is detailed below the standard of the tower, the base meets the city less surely than the shaft meets the sky, and the plaza at the foot, rebuilt in the 1990s, does not rise to the tower above it.
Movement V
The stake was real. The structural system was untried at a height only a few towers had reached, the financing faltered, and the face was one that many would find brutal. A defect in the foundations is recorded as found early in the building, and it is charged as a fault in the making of the base. The turn was made within modernism, not against it: the tower carried the tradition’s own claim, that structure should be honest, further than the tradition had dared, and that is why its swerve stands just below the bar the summit sets.
About fifty-seven years on, the form is whole and copied, the use unbroken in its original kinds, and the fabric stands with ordinary renewal; the plaza is the one addition of note, at the margin. The building has been studied without pause as the type case of the braced tube, and the return is mostly to how it stands: its meaning, once seen, is seen. It holds the household, labour and commerce, the city’s traffic and the wind off the lake in one structure, and the sacred, the state, history and death are absent from it.
On the desk it stands at 8.3 among the towers and frames of its kind. It stands above the Chrysler Building and the Empire State Building (each 8.1) on the system, while the older towers stand above it on The Sublime, The Archetypal Deep and The Imperishable; between the Lloyd’s Building (8.0) and the Centre Pompidou (8.4) among buildings of expressed structure; and below the Eiffel Tower (8.7), which made its iron into a public myth more fully. Its standing rests on The Made, The Imperishable and The Inner Law; what holds it is a myth only partly built, a return given mostly to engineering, and a world of one present tense.
Act III · The Twelve
Judged on purpose, structure and site, the subtractive test finds very little to take away. The taper is compelled by the stacked uses: the deep floors at the foot suit parking, shops and offices, the shallower floors above suit apartments, whose rooms need daylight within a few metres, and the narrowing top suits the observatory and the masts. The taper also does structural work, drawing the mass in toward the top and stiffening the tower against the wind. The diagonals are compelled by wind load at this height, and the economy of the building depends on them. What weakens the claim: the masts add a use, not a form, and in the apartments the diagonals cross some windows.
Score: 8.4 / 10
Two things can be stated in space, and they hold. The first is the vertical city: a person can be housed, employed, fed, parked and served in one structure, the street lifted into the air at a sky lobby, the city’s layers of use laid one on another; and the building made that a way of living, lived for half a century. The second is that a tall building is a cantilever from the ground against the wind, and that the forces can be shown and made the face of the thing. What holds the axis at 8.0 is that the first is a disclosure of convenience and density, and the second an engineer’s truth: the tower says how people may be stacked, and little of what the stacking does to them.
Score: 8.0 / 10
The elevation is real and frequent, of one cold kind. From the lake shore and the length of Michigan Avenue the black tapering mass, its diagonals reading as giant crossings at the scale of the city, carries a severe grandeur: the dread of weight held in the air, made legible. The taper makes the tower seem taller than it is and gives it the sloped stance of a mountain or a pylon rather than the flat cliff of a slab. From the upper floors the views over the lake and the grid are a sublime of their own, but they are the site’s, credited only as far as the narrow top frames them. At the foot the building is less moving: the plaza and the street level do not rise to the tower.
Score: 8.3 / 10
The archetype is built into the form, not applied. The truncated obelisk, the tower that narrows as it climbs and so reads as rooted and enduring rather than as a box stood on end; the diagonals, which add the figure of a thing laced and bound against the elements, a frame like a rigged mast or a trussed bridge stood upright; and the household above work above the street, a whole town in one shaft. All of it is legible, and all of it is the structure. But the archetypal content is thin beside the temple, the dome or the cathedral. The plan takes in no threshold, no centre and no sacred interior; there is no point where the whole is gathered and met. Myth evoked by form, and partly built.
Score: 7.8 / 10
The tradition the tower inherited in Chicago in 1965 was the steel and glass prism, its structure hidden behind a regular curtain wall and expressed only by applied mullions, its uses kept in single-purpose towers. The swerve is in three parts taken together: the structure moved to the outside and drawn in diagonals across the face; the taper, which broke the prism’s constant section; and the mixed-use stack at a hundred storeys. The stake was real: an untried structural system at a height few towers had reached, a financing that faltered, and a face many would find brutal. What holds the axis below the bar is that the turn was within modernism: it carried the tradition’s own claim, that structure should be honest, further than the tradition had dared.
Score: 8.4 / 10
Change the form and the building can no longer say what it says. Take away the taper and the stacking loses its fit: the apartments would be too deep, the offices too narrow, and the tower would read as a slab with no reason in its shape. Take away the expressed diagonals and its claim, that its height is earned and visible, goes with them, and its economy too. The form is the instrument by which a hundred storeys of mixed life are made possible and shown. It changes how purpose is lived as well: the sky lobby, the shared amenities halfway up and the parking inside the building make a resident’s day vertical. Inside the floors the form is less felt: an office here lives much as one elsewhere, save for the diagonal across a window and the view.
Score: 8.5 / 10
Evidence of return is steady. For more than half a century the building has been studied in structural engineering as the type case of the braced tube, and returned to in the histories of the skyscraper, of Chicago and of Skidmore, Owings and Merrill. It yields on return to the eye: the diagonals and the taper read differently from every distance and angle, and the X, which crosses the floors at unequal points, rewards attention. But the return is largely formal and technical. The building’s meaning, once seen, is seen; writers on architecture return to it to learn how it stands more than to learn what it is. That holds the axis at 7.8, below the buildings whose meanings are still contested after centuries.
Score: 7.8 / 10
The field is the tall building, above all in America in the second half of the twentieth century, and through it the tall building everywhere. The intrinsic force is high: the braced tube made the outer frame of a tower its main structure against the wind, and efficient enough to carry a hundred storeys of mixed use in one shaft; with Khan’s other tube systems, the framed tube before it and the bundled tube after it, it changed what height cost. Achieved reach is scored with intrinsic force: wide and documented in its field. The tube systems became standard knowledge of supertall structure, expressed diagonal bracing recurs on towers across the world from the later 1970s, and the mixed-use supertall became a common type. The reach is shared with Khan’s sequence of towers.
Score: 8.6 / 10
Weighed on form, use and fabric together, over about fifty-seven years. The form is whole: nothing of the governing idea has been lost, and the design has outlived the conditions of its making as a model copied and answered. The use is unbroken and in its original kinds, offices, apartments, shops and the observatory all in use. The fabric of steel, skin and glass stands with ordinary renewal, and the plaza at the foot was rebuilt in the 1990s, an addition at the margin. Its presence is wide in its field and in Chicago, below the widest of buildings of its age.
Score: 8.9 / 10
Techne includes structure and engineering, and here the making is load-bearing in the literal sense. The command of the structural medium is of the first rank: columns, diagonals and ties proportioned so that the whole face acts as one braced tube, meeting at nodes that carry the forces round the building, with a material economy that was the point of the design. The architectural command is of a piece with it: the taper resolved so that the diagonals stay true on faces that narrow as they rise, the black skin drawn tight over the frame so that it reads clean. The costs: the top and masts are resolved more roughly than the rest, the street level is detailed below the tower’s standard, and much of the interior is ordinary work.
Score: 8.9 / 10
One physics governs the whole: the X and the taper. Take the two most distant elements, the base with its shops and parking and the top with its observatory, its last apartments and its masts. Both obey the same law. The same diagonals cross the parking floors and the apartments; the same taper that widens the base for cars narrows the top for the view. The range is wide in use, car, shop, desk, home and view, and the law holds across all of it: narrowness is not coherence, and this is not narrow. Two things hold the axis at 8.7. The masts on the roof are a second law, the broadcaster’s, set on the first, and the base meets the city less surely than the shaft meets the sky.
Score: 8.7 / 10
The orders held in one structure are the household and dwelling; labour and commerce; the city and its traffic; and the natural order, in the wind the structure is shaped against and in the lake and the horizon the top frames. They are integrated, not listed: the structure that answers the wind is the same that makes the stack of home and work possible, and that hold is wider than a single-purpose office tower can reach. What holds the axis lowest of the twelve is what is absent or thin: the sacred, the state, history and death. The tower holds the city’s present tense and little else, narrower than a building that gathers a people’s worship, government or memory. The figure describes the form.
Score: 7.4 / 10
Act IV · The Reckoning
8.3 / 10 · Final Average
Placement: Tier IV · Canonical
Strongest Dimensions
The Made and The Imperishable at 8.9, then The Inner Law at 8.7 and Pressure on Tradition at 8.6. A frame in which columns, diagonals and ties act as one braced tube, with the taper resolved and the black skin drawn tight over it; a form whole after about fifty-seven years and a use unbroken in its own kinds; one law of the X and the taper held from the parking at the foot to the view at the top; and a structural system that changed what height cost and became standard knowledge of the tall building.
Limiting Dimension
The Encompassed at 7.4: the household, labour and commerce, the city and the wind are held in one structure, and the sacred, the state, history and death are absent. Below the rest, The Archetypal Deep and The Bottomless Well at 7.8, then The Unconcealment at 8.0: the obelisk and the bound frame are evoked by the form but the plan gathers nothing; the return is to how the tower stands more than to what it is; and the vertical city is disclosed as convenience and density, how people may be stacked rather than what the stacking does to them.
The Necessity Cap clears at 8.4 against a threshold of 7.5. The Coherence Floor clears: The Living Form at 8.5, The Made at 8.9, The Inner Law at 8.7, each against 7.0. The Epochal Gate is unmet: The Imperishable at 8.9 and Pressure on Tradition at 8.6 clear the bar of 8.5, but The Swerve at 8.4, The Unconcealment at 8.0 and The Archetypal Deep at 7.8 fall short. The Universal Minimum is met (no axis but The Encompassed falls below 7.8, against 7.5), and The Encompassed, which is exempted, clears its own floor of 6.0 at 7.4.
Basis · a reading from knowledge of the John Hancock Center as it stands in 2026: its documented form, structure, stacking of uses and history in outline. Knowledge is surest on the form, the structure and the history, thinner on the interiors and the apartment plans. No plan, survey, image or written source was consulted, and the building was not visited. The work scored is the tower as it stands: the braced steel tube with its taper, its black skin, its stacked uses, the observatory and the masts on its roof, and what has been built onto it in its life as that work, the plaza at its foot as rebuilt in the 1990s and the observatory’s later fittings among it, which belong to the one work and are credited or charged to it. The tower itself has not been rebuilt; the plaza at its foot has. The Water Tower and the rest of Michigan Avenue are context and are not scored. The design is credited to Skidmore, Owings and Merrill, Chicago office, with Bruce Graham as design partner and Fazlur Khan as structural engineer; the structure is as much the engineer’s as the form is the architect’s, the two are one work, and collaboration is not charged. The builders are not named. Nothing is quoted. Facts that could not be verified are not given, among them the building’s present official name, the developer at the start and the lender and owner of the scheme, the length of the halt in building over the foundations and the details of their repair, the number of tiers of diagonals on each face, the weight of steel and its comparison with shorter frames, the height to the tips of the masts, the floors on which each use begins and ends, the amenities of the sky lobby, the operator and later enclosures of the observatory, the history of the restaurant at the top, and how much of the skin and glass is original.