Walk down Mission Street today and you’ll see it. It’s a 58-story luxury glass monolith that looks, at first glance, like every other high-end condo in the Financial District. But locals know better. They call it the leaning tower of San Francisco. Officially, it’s the Millennium Tower. Unofficially, it’s a billion-dollar engineering headache that’s been sinking into the soft mud of the Bay Area for over a decade.
It’s tilted. Not enough to make your coffee slide off the table—at least not yet—but enough that the engineers had to spend years and hundreds of millions of dollars trying to pin it to the bedrock.
You’ve probably heard the jokes. People compare it to the Leaning Tower of Pisa, but this isn't a medieval stone bell tower. This is a 645-foot residential skyscraper. It’s got a lap pool, a wine cellar, and some of the most expensive real estate in the city. Yet, by 2016, the building had sunk 16 inches and tilted several inches toward the northwest. That’s not supposed to happen. Modern engineering is meant to be boring. This was anything but.
Why the leaning tower of San Francisco started sinking in the first place
Basically, the whole thing comes down to dirt. San Francisco is built on a messy mix of landfill, sand, and what geologists call "Old Bay Mud." Most skyscrapers in the city are anchored by piles that go all the way down to the Franciscan graywacke—the solid bedrock.
The Millennium Tower didn't do that.
Instead, the developers, Millennium Partners, used a "friction pile" design. They drove 950 reinforced concrete piles about 60 to 90 feet deep into the dense Colma sand. The idea was that the friction of the sand against the piles would hold the building up. It’s a common technique for shorter buildings. But for a heavy, concrete skyscraper?
It was a gamble.
By the time the building opened in 2009, it had already settled several inches. The developers didn't tell the buyers right away. In fact, the public didn't really find out until 2016. By then, the "settlement" was far beyond the original estimates of 4 to 6 inches over the life of the building. It was a disaster. It was sinking fast. And it was leaning.
Lawsuits started flying. Homeowners, who had paid millions for their "homes in the clouds," watched their property values crater. The Transbay Joint Powers Authority, who were building the massive Salesforce Transit Center next door, got blamed. The developers said the construction of the transit center drained groundwater, causing the soil under the tower to compress. The Transbay folks fired back, saying the building was just too heavy for its foundation.
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Honestly, it was a mess.
The $100 million "Fix" and why it almost made things worse
Imagine trying to jack up a 58-story building while people are inside sleeping. That was the goal of the "Perimeter Pile Upgrade."
The plan was relatively straightforward on paper: drive 52 new steel piles 250 feet deep into the bedrock and tie them to the building’s existing foundation. It’s basically like putting a kickstand on a bicycle.
But engineering in the real world is rarely that simple.
In the summer of 2021, while they were installing these massive piles, the building started sinking faster. It dropped another inch in just a few weeks. Work had to stop. The city was on edge. Critics like Jerry Dobson and other structural experts began questioning if the fix was actually accelerating the tilt.
The engineers eventually figured out that the drilling process itself was vibrating the soil and causing more settlement. They changed the methodology, switched to a different drilling technique, and finally—after years of delays—finished the "fix" in 2023.
Does it work?
Sort of. The building is now "pinned" to the bedrock on two sides. This has stopped the sinking on those sides and has actually helped pull the building slightly more upright. It’s not perfectly straight, and it likely never will be. But it’s stable.
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Living inside the tilt: The human cost
You have to feel a little bad for the residents. These aren't just faceless investors; many are people who put their life savings into what they thought was the safest bet in San Francisco.
Imagine spending $4 million on a condo only to find out you can't sell it. Or finding out your building is the punchline of late-night talk show monologues.
There were reports of "ghostly" creaking sounds at night as the building shifted. Some residents famously filmed marbles rolling across their hardwood floors to prove the tilt. One resident, Frank Jernigan, even posted a video showing a golf ball rolling toward the corner of his unit.
The legal settlements eventually reached roughly $100 million to cover the repairs and compensate homeowners for the loss in value. But the stigma remains. Even though the leaning tower of San Francisco is technically "fixed," would you want to buy a unit there?
It’s a tough sell.
The engineering legacy and what we learned
The Millennium Tower isn't just a cautionary tale for San Francisco; it changed how skyscrapers are built in seismic zones.
Before this, the "friction pile" method was seen as a viable, cost-saving alternative for certain sites. Now? Good luck getting that through a planning commission for a high-rise. The city of San Francisco actually tightened its building codes and oversight processes because of this debacle. They now require more rigorous independent peer reviews for foundation designs on tall buildings.
There's also the groundwater issue. We now know that deep excavations in urban environments can have a "straw effect," sucking water out from under neighboring buildings. This causes the soil to consolidate. It’s a phenomenon called subsidence.
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- Bedrock is king. If you're building over 500 feet, you better touch the rock.
- Soil isn't static. It breathes, moves, and reacts to everything around it.
- Transparency matters. The years of secrecy between 2009 and 2016 only made the legal fallout worse.
Actionable insights for homeowners and investors
If you're looking at real estate in a city known for "soft" soil—like San Francisco, New Orleans, or parts of New York—there are things you need to do before signing a contract.
Check the Geotechnical Report
Every major development has one. It tells you what the building is sitting on. Is it bedrock? Is it "Old Bay Mud"? If the building is tall and isn't anchored to bedrock, you should ask why.
Look at the Settlement Records
All buildings settle. It’s normal. But the rate of settlement should be predictable and diminishing over time. If a building is still settling significantly five years after construction, that’s a red flag.
Understand the "Zone of Influence"
If you're buying next to a massive planned construction project (like a new subway or a transit hub), recognize that the dewatering required for that project could affect your building’s foundation.
Insurance and HOA Disclosures
Read the HOA meeting minutes. That’s where the "boring" problems show up first. If there are mentions of cracked drywall in the lobby or doors that don't quite latch, those are often the first signs of structural movement.
The leaning tower of San Francisco is a reminder that even the most impressive feats of human engineering are ultimately at the mercy of the earth beneath them. It’s a fascinating, expensive, and somewhat terrifying lesson in geology.
The building is staying put for now. The piles are in the rock. The marbles might still roll a little bit, but the nightmare of a continuous sink seems to have been averted. It stands as a monument to the importance of doing the foundational work right the first time—because fixing it later is a whole lot harder.