In Santos, Brazil, apartment towers along the Atlantic coast have slowly tilted by feet. The buildings are still homes to thousands of people. Now engineers are working on a solution that could cost millions of dollars per tower.
SANTOS, Brazil – From the beach in Santos, the skyline can look as if someone has pushed it sideways. Along the waterfront of this Brazilian coastal city, dozens of apartment towers rise 10, 15 or even 20 stories into the sky – except they do not rise perfectly vertically.
Some visibly lean toward their neighbors, creating a surreal urban landscape that has made Santos famous far beyond Brazil. For people walking along the beach, the effect can be startling. The towers look as though they are slowly sliding toward one another.
To residents, however, the most obvious evidence of the problem can be much more mundane: a ball placed on the floor begins to roll, cabinet doors swing open by themselves, and furniture may need to be wedged into position.
The buildings have become one of Santos’ unofficial landmarks, sometimes compared with Italy’s Leaning Tower of Pisa.
But unlike Pisa, the phenomenon is not the result of a medieval construction mistake. It is a story about modern apartment towers, a rapidly expanding coastal city – and an unusually difficult piece of geology hidden beneath the streets.
A City Built on a Geological Trap
Santos sits on Brazil’s Atlantic coast, about 70 kilometers from São Paulo. Its beachfront became a prime location for apartment construction during the middle of the 20th century, particularly from the 1940s through the 1970s.
The problem was beneath the buildings. The upper layers of soil along much of the waterfront consist of relatively compact sand. Beneath that is a far less forgiving material: thick layers of soft marine clay containing large amounts of water.
Engineering studies of the Santos waterfront describe a typical profile in which a sandy surface layer is followed by many meters of soft clay, with much stronger soil or rock occurring much deeper underground.
In some areas, the competent layer is roughly 45 to 60 meters below the surface. That distinction is crucial. The sand was capable of supporting buildings – at least initially. So during the construction boom, many towers were built on relatively shallow foundations resting in that upper sandy layer.
The foundations were not necessarily considered reckless by the standards of their time. The problem was that the buildings were enormous loads sitting above a thick, compressible layer of marine clay.
And clay does not behave like rock. Under sustained pressure, water slowly drains from the clay and the soil consolidates. The ground settles. If every part of a building settled by exactly the same amount, the result would mostly be a building that simply moved downward.
But that is not what happened in Santos. Different parts of the ground settled by different amounts. The result was differential settlement – and that is what turned straight towers into leaning ones.
The Buildings Did Not Suddenly Start Falling
One of the most important things to understand about Santos is that these buildings did not simply begin tipping over one day. The movement developed gradually, over decades.
As more towers were constructed along the waterfront, their loads affected the soft clay beneath and around neighboring buildings.
The pressure zones produced by adjacent foundations could overlap in the deeper layers of clay, changing how the soil consolidated.
In some cases, neighboring buildings tilted toward each other. In others, buildings moved in different directions. This is why the skyline can look particularly strange: the towers are not all leaning in the same direction.
Researchers have documented cases in which the interaction between neighboring foundations contributed to additional settlement and increased inclination.
The result is sometimes described as a kind of geological domino effect. But there is an important caveat: the buildings are not literally toppling like dominoes.
The phenomenon is much slower, and the critical issue is the interaction between structural loads and the long-term behavior of the soil.
How Far Can a Building Actually Lean?
Far enough to make a perfectly ordinary apartment feel very strange. One of the best-known examples is the Núncio Malzoni condominium, built in 1967.
Its 17-story towers were constructed on shallow foundations. At one stage, one of the blocks had moved roughly 2.1 meters out of vertical alignment.
Engineering studies recorded an inclination of about 2.2 degrees in one of the blocks. Imagine taking a 55-meter-tall building and moving its top more than two meters sideways while keeping its base on the ground.
From the street, the effect is dramatic. Inside, the physics becomes almost comical. Residents and visitors can demonstrate the inclination simply by putting a small ball on the floor. It rolls.
An egg placed in a frying pan can slide toward one side. Doors and cabinet doors can behave differently from what people expect in a level apartment.
Brazilian media have documented residents describing exactly these everyday effects, as well as visitors experiencing dizziness when they first enter some of the most strongly inclined buildings.
For people who live there, however, it can become routine. The floors can be leveled with adaptations. Furniture can be shimmed. People learn where objects will roll. The extraordinary becomes ordinary.
So Are the Buildings Dangerous?
This is where the Santos story becomes more complicated than a photograph suggests. A building can look terrifyingly crooked without being on the verge of collapse.
The key distinction is between geometric inclination and structural failure. Engineers have spent decades studying the buildings, measuring their settlement and analyzing how the concrete frames respond to the loads created by their changed geometry.
The city has also required structural assessments of the most inclined buildings. In a 2015 municipal assessment, Santos reported that none of the buildings then under evaluation had been identified as presenting an immediate structural risk.
More recently, local reporting citing the municipality said that none of the city’s buildings had reached the maximum limit requiring an occupancy ban, while their inclination continues to be monitored through technical inspections.
That does not mean every leaning building is automatically safe. It means that the question cannot be answered by looking at the angle alone.
Engineers need to know whether the settlement is still progressing, how the foundations are behaving, whether the reinforced-concrete structure has suffered damage, how loads have shifted between columns and beams, and what the underlying soil is doing.
In other words, a crooked building is not necessarily a collapsing building.
The Núncio Malzoni Experiment: Can You Straighten a 17-Story Building?
Santos has already demonstrated that the answer can be yes. The Núncio Malzoni building became one of the world’s most remarkable examples of large-scale structural correction.
Instead of simply trying to stabilize the old foundations, engineers created a new foundation system capable of reaching much deeper, stronger ground. New concrete piles were installed beside the building, reaching roughly 56-60 meters underground.
Engineers then built a transition structure capable of transferring the building’s load to those new foundations. Finally, hydraulic jacks were used to gradually lift and reposition portions of the structure.
The process was extraordinarily delicate. The building could not simply be lifted several feet in one movement. It had to be manipulated in tiny increments while engineers monitored the structure and the foundations.
At one point, hydraulic jacks were used to raise different parts of the building by different amounts. The correction ultimately returned the building to a substantially vertical position.
The project became a major engineering case study because it demonstrated that an occupied, multi-story reinforced-concrete building could be transferred from problematic shallow foundations to a new, deeper foundation system and then carefully straightened.
But there was a catch. It was extremely expensive. And Santos has many buildings.
Why Not Just Straighten Them All?
Because doing so can cost millions – and every building is a different engineering problem. A correction project can require extensive geotechnical investigation, new deep foundations, structural reinforcement, hydraulic equipment, monitoring and careful control of the building throughout the operation.
There is also a fundamental economic question. If a building is structurally stable and its inclination is no longer progressing significantly, is it worth spending enormous sums to make it perfectly vertical?
Or is it better to monitor the structure and intervene only if the underlying problem becomes significant? There is no universal answer.
The appropriate solution depends on the soil, the foundation, the degree and direction of inclination, the rate of settlement and the condition of the building itself.
Santos Is Now Trying to Solve the Problem at City Scale
For years, the tilted buildings were treated largely as individual engineering cases.
That is beginning to change.
As of 2026, the Municipality of Santos says it is monitoring 65 buildings with significant out-of-plumb conditions, concentrated primarily between Channels 2 and 6 in the neighborhoods of Gonzaga, Boqueirão, Embaré and Aparecida.
In March 2026, the city announced discussions with Brazil’s National Bank for Economic and Social Development, or BNDES, about engineering solutions and possible financing for the buildings’ realignment.
The city says the basic engineering concept involves lifting the building with hydraulic jacks, constructing a new deep foundation and gradually transferring the building’s weight onto it. The proposed deep foundations would extend approximately 50 meters underground.
As of June 2026, however, financing was still being worked through rather than a citywide straightening program already being under construction.
That distinction matters. The future of Santos’ tilted skyline is therefore not a simple story of dozens of buildings about to be repaired.
For many of them, the more realistic near-term strategy may remain monitoring and stabilizing the problem, while the most technically or economically urgent cases are considered for major intervention.
Will All of Santos’ Leaning Buildings Eventually Be Straight?
Probably not – at least not anytime soon. There is a technical solution for some of the buildings. Santos has already proved that.
But turning dozens of aging apartment towers upright is not like repairing a row of streetlights. Every building has its own foundation geometry, soil conditions, structural configuration and history of settlement.
And the cost is borne, in large part, by the condominium owners who live inside the buildings. That is why the city is now looking not only for engineering solutions but also for financing mechanisms.
The municipality has described the problem as solvable, but has also emphasized that funding is essential to turn the engineering concepts into large-scale projects.
The Strange Part: The Buildings Can Feel Less Dramatic Than They Look
From the beach, the towers can appear almost impossible. Inside them, the experience is often much less dramatic.
A person standing in a tilted apartment does not necessarily feel as though they are standing at an angle comparable to the visible lean of the façade.
The human body and the room’s horizontal surfaces provide different visual and sensory cues, and many residents simply adapt to the geometry.
But the physical evidence is unmistakable. A ball rolls. A door moves. Furniture needs to be leveled. And visitors sometimes feel disoriented.
For residents who have spent decades there, these quirks can become part of everyday life. One resident interviewed by Folha de S.Paulo described the family even turning the building’s inclination into a kind of party trick: guests would watch an egg slide in a frying pan because the pan could not remain level.
That detail captures something important about Santos. The leaning buildings are not abandoned ruins. They are homes.
People raise families in them. They buy and sell apartments. They look out over the Atlantic every morning. Children grow up in rooms where a toy placed on the floor may slowly roll away.
A Warning Written Into the Skyline
The tilted towers of Santos are often compared with the Leaning Tower of Pisa. But there is a crucial difference. Pisa is a monument whose tilt became its identity.
Santos’ towers are living buildings whose tilt is the visible expression of a much larger geotechnical story.
Their existence is a reminder that a building’s safety is determined not only by concrete, steel and architectural design. It also depends on what lies beneath it.
In Santos, that hidden world is a thick layer of ancient marine sediment – soft, water-rich clay that has been slowly responding to the weight of the city for generations.
The most striking part of the story may therefore not be that the buildings are still standing. It is that engineers have learned how to understand, monitor and, in some cases, even reverse what the ground has done to them.
And in 2026, Santos is confronting the question on a much larger scale: whether it can find a way to straighten a skyline that took decades to tilt – without forcing the people who live inside it to pay the entire price.
Sources:
- Maffei, C. E. M. & Gonçalves, H. H. S. (2016), Innovative techniques used to plumb two 57 m height concrete buildings leaning 3.8 and 3.1%, Innovative Infrastructure Solutions.
- santos.sp.gov.br
- scielo.br
