Welcome to My Weird Prompts. I'm Corn.
I'm Herman Poppleberry. So Jerusalem's skyline right now — you can count at least a dozen tower cranes from basically any rooftop. The city's transforming in real time, and most of the conversation about it has been planning politics or affordability. Which is important. But today we're ignoring all of that.
Daniel sent us this one — he wants to look at high-rises purely from a construction technology and engineering lens. No zoning debates, no NIMBYism. Just the concrete, steel, elevators, and physics of building tall. He's asking six things specifically. How many skyscrapers are actually going up globally? What were the major breakthroughs that unlocked each height record? Which cities are densest per capita? Is there a dedicated subfield of high-rise engineering? What's the absolute ceiling on height with today's tech? And then — this is the curveball — if a city goes fully vertical, foundation to foundation, does all that weight actually change the geology beneath us? The answer to that last one turns out to be: yes, and the numbers are genuinely unsettling. So we're going to work through the whole list. Six questions, one deep-dive thread that goes from steel recipes to sinking cities.
The spine holding this together is material science and structural engineering, not architectural style. We're not going to debate which tower looks best. We're asking what keeps them standing, what prevents them from swaying people into motion sickness, and why after a certain height the laws of physics start sending you very direct memos.
Where do we start with the raw numbers? Daniel's first question was simply — are we building more high-rises globally, or has the boom peaked?
Let me give you the baseline. The Council on Tall Buildings and Urban Habitat — CTBUH, that's the international body that tracks all this — their mid-twenty-twenty-six dataset shows over sixty-two hundred completed buildings at one hundred fifty meters or taller globally. That's forty-five stories or up, roughly. In twenty-sixteen, that number was around forty-five hundred. So we're looking at roughly thirty-eight percent more skyscrapers in a single decade. The rate is not slowing down. If anything, it's shifted geography.
China still has about forty-five percent of all buildings over two hundred meters. That's the supertall threshold. But the fastest growth right now — the steepest part of the curve — is Southeast Asia and the Middle East. Vietnam and Indonesia are building at rates that make Shenzhen in twenty-eighteen look almost leisurely. And Saudi Arabia's pipeline, driven by the Vision Twenty-Thirty projects, is enormous. The UAE continues adding towers though they've been playing this game longer.
Israel specifically — since Daniel's watching Jerusalem cranes and specifically asked what's happening here.
Tel Aviv has around thirty buildings over a hundred meters. Jerusalem historically has about eight. But the Gateway project and new zoning frameworks are actively pushing the city toward its first two-hundred-meters-plus towers. It hasn't happened yet, but the planning is in place, and several are in the pipeline. What's interesting is Jerusalem sits on a more complex geological substrate than coastal Tel Aviv, which connects directly to the geological question we'll get to later. The city's on limestone and dolomite — the Judean Hills. Karst, cavities, ancient terra rossa pockets. You don't just pour a mat foundation and call it a day.
The skyscraper boom is accelerating, not plateauing. The sixty-two hundred number is the global baseline we should have in our heads. And Jerusalem and Tel Aviv are both climbing the height ladder, even if Israel is hardly in the top tier of skyscraper counts.
Now, Daniel's second question — the major breakthroughs in height. And this is a story that isn't really about inventing new exotic materials most of the time. It's about optimization. Let me trace the timeline. The Home Insurance Building in Chicago completed in eighteen eighty-five. Forty-two meters. To us, that's a mid-rise apartment block. To eighteen-eighty-five, it was revelation — the first building using a structural steel frame instead of load-bearing masonry walls. That distinction matters. Before steel frames, the walls held everything up, which meant thicker walls limited window size and building height scaled with masonry weight.
Steel changed that because it could hold the load while the walls became basically curtains.
The real unsung hero here is the Bessemer process from eighteen fifty-six, which made structural steel affordable at scale. Without cheap steel, no Chicago School of architecture. You'd just be stacking brick on brick until the bottom floor became a grim, windowless bunker. Then in eighteen fifty-three, Elisha Otis demonstrated the safety elevator — the thing that actually made upper floors desirable instead of servant quarters and storage. Before that, people were not going to climb twelve flights of stairs daily.
Stairs as social class filter — the higher the floor, the less you paid. The elevator inverted that model entirely. Suddenly the top floors were the penthouses.
Inverted the economics of verticality. Fast forward to nineteen thirty — the Chrysler Building, three hundred nineteen meters. That leap came from riveted steel frames and the willingness to build slender, tapering forms. Wind engineering at that point was mostly — hope the shape works. Then you have about a forty-year wait for the next layer: tuned mass dampers.
That's the giant pendulums inside skyscrapers, right? Multi-ton weights that swing opposite the building's motion to cancel sway.
First major installations in the nineteen seventies — the Citigroup Center in New York has a four-hundred-ton concrete block on a sliding bearing. The principle is straightforward: when wind pushes the tower, sensors detect the movement and motors or passive pendulums push mass in the opposite direction. Without this, people on upper floors during wind events start feeling queasy. The human vestibular system is sensitive to acceleration, not just displacement — even millimetres of sway at the right frequency and people literally get motion sick.
The glockenspiel of corporate vertigo prevention, hidden in a concrete block.
After dampers came advances in high-strength concrete. By the nineteen nineties, we had concrete grades of C-eighty to C-one-hundred — meaning compressive strengths of eighty to a hundred megapascals, roughly eight hundred to a thousand kilograms per square centimetre. Older concretes were in the forty megapascal range. Going to twice the strength lets you pour columns that are thinner for the same load or taller for the same column diameter. Burj Khalifa in twenty-ten uses grade C-eighty and C-sixty concrete for different portions. Then you add outrigger systems — these are horizontal structural members that connect the building's core walls to perimeter columns, so the whole tower behaves like one system resisting lateral loads. Belt trusses wrap around the perimeter to distribute the force. Those got refined tremendously in the two-thousands and are now standard practice in supertalls over sixty stories.
If I'm charting this right: Bessemer steel, safety elevator, tuned mass dampers, high-strength concrete, outrigger systems — those are the five breakthrough categories.
One more: foundation technology. Jeddah Tower, which is expected to push past the one-kilometre mark when it completes, is not just tall above ground. It sits on a mat foundation three and a half metres thick. Underneath that, two hundred and seventy bored piles, each one and a half metres in diameter, driven a hundred and ten metres into the earth. That is deep enough to bury a thirty-story building. For one foundation. The ratio of underground to above-ground engineering has been shifting — modern supertalls often have fifteen to twenty percent of their structural engineering budget below the surface.
Which connects to Daniel's fifth question directly — what's the ceiling on all this? Is there some absolute height limit with today's technology?
There are two main ceilings. First, the material ceiling. Concrete — the highest-grade stuff we can reliably pour and pump — maxes out around grade C-one-hundred-twenty to C-one-hundred-thirty. With that, structural engineers estimate the theoretical maximum height is roughly sixteen hundred meters. That's almost exactly one mile. After that, no matter how clever your form, the weight of the structure above starts to crush the columns below. It's called the self-weight problem. Concrete at the base of a theoretical mile-high tower would be bearing so much load that it's flirting with its own compressive strength limit before you factor in any live load — people, furniture, wind.
Everything above that point is just an elaborate way to crush itself.
It's literally stone eating itself. But there's a second ceiling: elevator rope weight. Standard traction elevators use steel cables. Those cables hang from the top of the shaft. At around five hundred meters, the rope itself — its own weight — exceeds about thirty percent of the elevator's total lifting capacity. Go higher and the rope weight so dominates that you need vastly heavier cables, which require bigger motors and impose more structural load. The economic crossover point for conventional steel-rope systems lands around five hundred to six hundred metres of shaft height. Beyond that you're paying more and more for less and less capacity. The proposed solution to both ceilings — ThyssenKrupp's MULTI system from twenty-seventeen — eliminates the rope entirely. Multiple cars travel in a loop shaft using linear motor technology, moving vertically and horizontally. No counterweight, no rope. That would be the key to mile-high buildings. And it's not widely deployed yet.
Frank Lloyd Wright drew "The Illinois" — the mile-high tower — in nineteen fifty-six. But you're saying in twenty-twenty-six we actually have most of the structural capability to build it. The first-order technology exists. We just can't get people above floor six hundred without putting them on an inclined horizontal shuttle loop.
That's essentially it. The concrete's there. Wind aerodynamics are solvable — Burj Khalifa's Y-shaped floor plan reduces wind forces by about twenty-five percent compared to a rectangular tower of equivalent height. Jeddah Tower will push past one thousand and eight meters using that tapered triangular form and those massive piles. Carbon fiber reinforced composites could theoretically push to two thousand meters or beyond, but cost is so prohibitive that nobody has run the serious financial analysis. So the true ceiling is physics crossed with elevator logistics and economics.
Let's talk about cities and density then. Daniel's third question — highest per capita concentration of skyscrapers.
Hong Kong is the outlier among major cities. Roughly three hundred and fifty-five buildings over one hundred and fifty meters serving a population around seven and a half million. That's one skyscraper per twenty-one thousand people. New York is similar in raw count — about three hundred such towers for eight and a half million, so one per roughly twenty-eight thousand residents. It's in the same ballpark. But Shenzhen, which built about a hundred and ninety of those towers, has a population closer to seventeen and a half million. So it actually sits at about one per ninety-two thousand people.
That's a vastly different feel on the ground. Hong Kong and New York feel like extreme verticals. Shenzhen's towers are spread out or the city is just huge.
But the actual per capita skyline density winner is Monaco. Roughly one skyscraper per eight thousand people, because the available land is vanishingly small and the only way to go is up. Monaco doesn't have a huge absolute number of towers — something like eight to ten over one hundred fifty meters — but the population is tiny. Extreme land scarcity produces extreme tower-per-person ratios. This also reflects building typology: Monaco's towers are residential; Hong Kong's are heavily residential mixed with office; Manhattan is office with recent residential infill.
What's Israel's per capita? Northern Tel Aviv plus Ramat Gan's stock?
Israel would be much lower. Maybe one high-rise per one or two hundred thousand people. The high scores happen where every square metre of land acts as a constraint. So you either compete globally and tell me what Daniel was asking — is there a specialized sub-discipline devoted purely to high-rise construction? Because these structures differ from, say, a sports stadium or a six-story car park in pretty fundamental ways.
And I find the existence of this formal sub-discipline satisfying. Within the American Society of Civil Engineers — ASCE — there is a specific technical council on tall buildings and urban habitat. The structural engineering firms that win most of the supertall towers worldwide have dedicated "tall building design" groups — Arup, Thornton Tomasetti, SOM. These are engineers whose entire careers are the physics of towers stretching above about two hundred meters.
The CTBUH itself functions as the industry's home base — it publishes its own categorized database on every serious building, holds the annual Tall Buildings Conference, defines categories like "supertall" as above three hundred meters and "megatall" as above six hundred meters.
The criteria are extremely technical, and they go deep into assessment and forensic investigation of successful and failed designs. Meanwhile, there's a dedicated peer review journal — The Structural Design of Tall and Special Buildings — entirely focused on the problems particular to gaining altitude in the built environment. High earthquake zones, typhoon zones, weak soils... They're publishing detailed response analyses that inform actual foundation and damper designs for real projects everybody recognizes.
Under the heading of 'supertall engineering,' these firms and practices have produced everything from novel tuned liquid dampers to perimeter diagrid arrangements that channel loads along the whole skin of the building. They essentially treat wind loading like three different separate movement vectors happening simultaneously and combat them with shape rather than just counterweights.
Yes, engineering firms like Thornton Tomasetti routinely test supertall formwork with computational fluid dynamics — proper CFD — to shape the building's profile for minimal wind drag. That's why many newer high-rise silhouettes aren't perfectly straight extrusions; there are curves and chamfers calculated not by architectural whimsy but by aerodynamic necessity, by how the movement of air stresses certain joints. So we can say yes. That's the answer to "Is there a subset who do this full time?" Absolutely, it's vibrant and global.
Now we get to the most provocative question Daniel asked. If a city built out so heavily — like Manhattan to the horizon's vanishing point, uniform high density with high-rise foundations in all directions — would all that concentrated weight change the geology underneath, literally shift bedrock or the way stresses travel?
This is where the real minds of geology, structural safety, and geotechnical sensing meet, and the answer is unequivocally yes. And it's very poorly accounted for outside professional risk modeling.
Take one supertall — start with a discrete unit.
The Burj Khalifa weighs about five hundred thousand tonnes. Imposing that onto a chosen specific footprint pushes a significant localized load into deeper strata toward the Earth's upper crustal plates. Now take cities generally — multiply that behavior cumulatively. For Manhattan, multiple separate engineering modeling exercises — some from twenty-twenty-three and twenty-twenty-four — estimate the total above-ground imposed weight of its district built environment in the neighborhood of a hundred twenty-five million tonnes. That count doesn't fully add subway infrastructure or vehicular loads. And it's sitting on Pleistocene-era deposits of weathered metamorphic substrate above bedrock that's not infinite rigid resistance — it deforms.
One hundredtwenty-five megatonnes causes what precisely?
It sits on top and acts like a weight on a rubber kneaded natural crust — a gentle bulge of compaction formation migrating.
Lay out the connection between vertical load and surface stability gradually. Walk me through the unit mechanics.
The Earth's crust has a degree of isostatic response where sustained loading produces a tiny subsidience rate: certain established systematic survey data — almost wholly physical, via global positioning arrays and synthetic aperture radar applied over decades — indicates areas containing very dense structural weight loads subside at higher-than-reference rates when groundwater and other factors remain equal in statistical modeling of the base case.
One perfect testing ground consistent enough this has been quantified is relatively well-instrumented city control survey frameworks. So datasets with sixty-plus-year precision show consistent settlement signals measurable against a static geodetic benchmark outside the stressed zone.
You're exactly probing what structural and civil engineers now refer to as induced compaction, a share that shows district variance from simple clay packing alteration. Manhattan's probable incremental loss of elevation has numerous borehold load-measure reports from the forties onward. A slice extracted and collated by analysts in Earth's Future (published twenty-twenty-four in conjunction with several university earth-and-environment collaborations) gives a plausibly isolated structural-only metric: one to two millimetres of descending vertical shift per year caused by not groundwater pumpdown — common beyond the precinct near other underlying conditions — but just stable heavy buildings pressing downward.
Two millimetres per year over eighty earthly traversals feels invisible, but in a century...
Eighty plus above previous settlement cycles resulting only from heavy point load settling city core plus upper mass transport margins, leading linearly toward eight inches in a static-linsed geographical band. A kind of deliberate descent unlike generic tides. The hazard enters that a given portion can interline with simultaneous hazards from aquifer changes adding another millimeter — quicker if pulled down simultaneously — compacting cumulative aquifer exposure collapse heights within margins relevant to gravity-fed flood defense zones.
We in effect can lower the margin—
Lowering two or three spatiotemporal millimetres every cycle while the surfaces rise because we haven't reduced loaded footprint count eroding permanent hard coastal outlets — and Shanghai Pudong has given a sort-of direct close-coupled observation window: old quarter metropolitan cells sank less stably — two millimetres might echo inland depression changes, but Pudong (a newer high structure megadensity precinct placed since nineteen ninety onward) declined much faster.
These urban observation reports span five times the new block's annual slide pressure from weight alone collapsing aquifer margin versus the quiet quarter observing potentially up to five hundred percent relative surface descent every pass.
Precisely the wedge — because new high design includes intense mat column matrix infiltration restraining flow inside urban clay pack from raising up; so rate detection doubles. Without getting too lab-dataset-y, the emerging understanding is: our building constructs wick instability beyond safety value tolerance unless zones are rewater-normalised soon, since adjacent to — and crossing into the Hayward Fault right next to built rapid obs during earthquakes — added distributed surface-load can tip fault movement rate. Document field reasoning out of the same twenty-twenty-four piece suggests a circa five to probably the upper end of fifteen percent rise in simulated slippage over a multi-tenor timeframe. One could scarcely conjure clearer parallel human calibration errors accumulating misplaced stress models currently unprepared.
Fiveto-fifteenpercent more earthquake onset seems ridiculously careful. In a next-generation city becoming crowded, one improbable jolt makes more damage where frames warp inward atop fallen patch displacement.
Geologists appear — "unworked stone recleaves underneath to capture shifting.
This is precisely what should trouble or have mayors and resilience officers insisting on scanning, on routinely doing micro-deformation mapping combined with AI displacement alerts enabled sector by sector, block by mega-block, improving neighborhood stabilization adjustments before trapped waves deform basement walls ten stories down.
It used to belong only "raise grade higher." That meant absolute rechecking street drainage slope ratios redesigned higher instead minimal — consistent precision incline maintaining fast emergency washing mechanism capability toward absorbing monsoon flow events concurrent with coastal ingress; for all impervious plaza load region redistributed surface moving away alignment. Coastal cities regularly subsidencible should mandate tilted engineering gradient trackable on dashboard.
The worst lag factor is aquifers getting permanent squeezed from packed skyscraper foundation meshes over cover compressives tightening around — diminishing underground fresh reserve where any reclaimed system top-off usually trickle-feed injection reversed ratio fails to force out less now — Mexico City gets about sixty percent from groundwater but building weight increase disproportionately and anywhere active descending pack becomes lost dense stone forever altered during construction cycles stressing hydration capacity from thousand-year sourcing embedded far beneath.
All of those numbers connect concisely back to structural piles — you and I mentioned massive shafts transferred stack-plus surface combination avoiding nearby void — that weight eventually someways must go onto the side far lateral escaping manageable ret... settlement toward their grade lateral path shifted — where even inert rock with microdefects yields under maximal values added continually the deeper one goes constructing footprints entirely blocking out soak absorption passive recharge — and in all these models across San Francisco running inputs through program-feed within — emergent conclusion same quiet but unambiguous: dense vertical mass loading does compress far enough Earth-parameter non-isotropic.
Having sailed through hypertall— and the hidden foundation tension stored releasing upon reorientation reaction shifts— do prospective forward planners get updates handed meaning future downtown core maximum-build analysis proactively holds better regional modeling safe limits before hitting cascaded alarm along any contiguous fault? Is it embedded municipal regulation anywhere?
London for deep soil proximity constraints mandate, sort of structural cell-max guidance alongside heritage ancient base disturbance criteria, but very few nations wrote binding urban thickness loading slope policy guidance yet— a handful of Southeast spots directly impose neighborhood weight caps distributing bulk to less core-column-dense compact on specific newly stretched clays mapped back bay coastal flats across Jakarta region.
At least we've outlasted wondering "does weight matter." How amusing tall-building code cycles omitted assigning Earth-cascade safe offset belt time when faster water-clay weighting locked into ten metropolis run-lowered beneath buffer-tolerable delta level within two cycles rising combined storms... if not systematic survey-led loading-rules coverage still the hollowness in the pyramid, very slowly tilting the pyramid— and so a newer discipline crop becomes more vital each building applying deeper, heavier towers horizontally clumping.
Call it urban geophysics — slightly aspirational emergence field fusing engineering geology with structural dynamics anchored for protecting citiscape from own weight.
Or declare that making genuine civilization sink-awareness regulation.
### Earthbound summarizing tail observation
First, materials and known tallwind building define tangible max until lifts advance; present steel plus best concrete gets safe upper theoretical top of 1600 odd metres, just past measurement one mile over grade set large positive limit even imagination possible today.
Highest ranked per-cap verticality happens where area forced tiny — Hongcouver macro-zoned demands rooftop pattern keeping open — the dedicated engineer designs never generic five-over-one...
Primarily is skyscrapcity specialization reality fully staffed subdiscipline interlocking firm experts cooperating with city data. Then curve fascinating returns: weight-building produce gentle depressed down yielding increase threats from quake-time plus thirsty ever-min compressive shallw subsurface making matter pushed always proportionally more south east spreading – today existing field set marking deep footing toward keep groundwater moderate. Front yard plus vehicle remains trivial – underground megaton block compound multiplied.
### Takeaway delivery pair approach
Explicit easily remembered operational equation— next city tower proposal permit hearing call back actual soil report question pushed determined: "Resting composition secured buried water at Bedrock, or hitting loose drain unconsolidated saturated lacustrine empty fill increasing sliding sink dozens triple-rate?
Clarify ask municipal continuity must invest vertical fullcycle engineering specifically embedding long observe grade layer transform prior to shoving economic shortcut quick-turn compacts a dead residual mineral.
### Fun twist diversion
Herman (but Corn smiles giving cue): And now connecting through crisp fun as always; regarding unrelated random odd domain came by signature: "And now: Hilbert's daily fun fact." Under world of microbial ancient deliberate flavor transformation time windows across isolation northern archipelago horizon...
Hilbert: During the eighteen-eighties among the exiled prison settlements of Sakhalin, convicts fermented edible seasonal bull kelp with leftover hardened rye bread and accidentally produced a piquant carbonated brine later officially described by Russian naval medical officers as ‘criminal cola.
—
[pause] Thank you, Hilbert. That is staying with me not...
—
Concluding tie strongly asking wonder openly: The mile–height vertical meta city begins definitely feasible yet bottom where crowd summit dense dynamic deform margin unmapped truly spontaneous self field test outcome re–emerging pushed inside unknown unstable tier…
Herman encouraged invite interest softly: Please if one geotech acquainted raise human reach horizon drop their friend who lives near new tower happen presently mid routine shifting built – pass link recorded full share subtly instructive notion line engineering extra standard no merely heavy matter though redesign momentum steadily real-time shaper. Pitch questions anytime via myweirdprompts.thank our neighbour and producer Hilbert Flumingtop. well from Corn and me Herman.
This has been My Weird Prompts.
