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Between 1942 and 2024, the city gained an area equivalent to 2,318 soccer fields on top of Guanabara Bay, and that’s just part of the story. Centro, Flamengo, Glória, Urca, Saúde, and part of Lapa are located where there was once sea, lagoon, or swamp.
The Rio de Janeiro that appears on postcards is, in large part, an engineering feat. Data from the Pereira Passos Institute (IPP), the Rio City Hall’s planning body, show that between 1942 and 2024 alone, the city advanced 16.55 square kilometers into the sea, an area equivalent to 2,318 soccer fields the size of Maracanã. Fifty-six beaches have disappeared since the 20th century, the number of islands in Guanabara Bay dropped from 100 to 65, Lagoa Rodrigo de Freitas has shrunk by almost half, and two of the four hills that marked the city’s founding were literally razed. The neighborhoods of Centro, Flamengo, Glória, Urca, Saúde, Gamboa, and part of Lapa are located where there was once sea, lagoon, or wetlands. The first intervention of this type occurred in 1779, almost 250 years ago. The most famous, the Flamengo Landfill, will turn 60 in 2025.
What few Cariocas know is where these changes left marks that can still be identified with the naked eye.
What you will understand in this text
- How much of Rio de Janeiro’s area is, in practice, land reclaimed from the sea.
- Why two entire hills were dismantled in just over 30 years.
- How Lagoa Rodrigo de Freitas lost almost half of its water surface.
- Where you can still see, today, the marks of the original landscape.
- Why the world’s largest urban waterfront park was born from a demolition.
The scale few Cariocas know
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According to O Globo, in just 82 years, between 1942 and 2024, the city gained 16.55 square kilometers over Guanabara Bay. To give you an idea, this area is larger than the entire Ilha do Governador combined with Ilha do Fundão. But this number is far from telling the whole story. It refers only to the period documented by the IPP with aerial photographs. The landfills began much earlier.
The first recorded intervention occurred between 1779 and 1783, when Viceroy Luís de Vasconcelos ordered the demolition of a small hill in the Centro to fill a lagoon that was next to the sea. On the reclaimed land, the Passeio Público was built, designed by Mestre Valentim. It was Brazil’s first public garden. And also the country’s first urban landfill.
From then on, the city never stopped advancing over the waters.
The century when two hills disappeared
Rio’s most radical engineering took place in the 20th century. It wasn’t just about dumping earth into the sea. It was about demolishing entire mountains to use the material as landfill.
Morro do Senado was the first. Between 1900 and 1910, during Mayor Pereira Passos’ administration, the entire hill was razed to provide earth for the construction of the city’s new port. The material flowed down the street and ended up in the current neighborhoods of Saúde, Gamboa, and the old Saco de São Diogo, an area of sea that extended into the continent. Today, where Morro do Senado once stood, is Praça da Cruz Vermelha.
Morro do Castelo was the second, and its loss is considered one of the most symbolic in Brazilian urban history. It was on Morro do Castelo that, since 1567, the heart of the city founded by Estácio de Sá was located. There stood the Church of São Sebastião, colonial forts, 17th and 18th-century mansions, and even the mortal remains of the city’s founder himself. In 1922, under the argument of modernizing Rio for the International Exhibition of the Centenary of Independence, mayor Carlos Sampaio ordered its complete demolition.
All the removed earth was used to landfill Urca, expand Lagoa Rodrigo de Freitas (in fact, shrink it), create areas in the Botanical Garden, and reshape stretches of Guanabara Bay.
Result: of the four hills that marked Rio’s initial occupation (Cara de Cão, Castelo, Santo Antônio, and São Bento), two were erased from the landscape in less than half a century.
And the third hill also did not escape.
How a hill became the world’s largest waterfront park
The history of Morro de Santo Antônio is the history of Aterro do Flamengo. The two intertwine.
Between 1952 and 1958, during the administrations of mayors Dulcídio Cardoso and Francisco Negrão de Lima, Morro de Santo Antônio was completely dismantled. The removed material totaled millions of cubic meters of earth. This material was dumped on the Bay’s waterfront, creating the land where, years later, one of Brazil’s greatest postcards would emerge.
But the area remained for years as a desert of rubble.
It was architect and landscape designer Lotta de Macedo Soares who suggested to Governor Carlos Lacerda to transform the newly created strip of land into a large urban park. Lacerda bought into the idea. The urban and architectural projects were handled by Affonso Eduardo Reidy, and the landscaping by Burle Marx. Works began in 1961.
On October 17, 1965, the Aterro do Flamengo was officially inaugurated as Parque IV Centenário. The city’s 400th anniversary was being celebrated. Today, the total area reaches about 2 million square meters, with 7 kilometers in length and over 12 thousand trees. In 2012, it was declared a UNESCO World Heritage Site, in the “Urban Cultural Landscape” category.
The detail that seems contradictory: the world’s largest urban waterfront park was literally born from a demolished mountain.
The lagoon that was twice as large
Another case that measures the transformation is Lagoa Rodrigo de Freitas, today one of the postcards of the South Zone.
Comparing the map drawn in 1809 by Lieutenant Colonel Carlos José dos Reis Senna with the IPP survey conducted in 2024, the water mirror area of the Lagoon decreased by 46 percent. It went from 4.1 square kilometers in 1809 to 2.2 square kilometers last year. Almost half of the Lagoon turned into a bank. Most of this reduction already happened in the 20th century, with successive landfills documented in aerial photos from 1928, 1942, 1975, 1999, and 2024.
The reduction created the neighborhoods, avenues, and buildings that today form the Lagoon’s waterfront.
The 56 beaches that disappeared
The list of beaches that disappeared from Rio is long. Geographer Jorge Luiz Barbosa, in an interview with O Globo newspaper, identified 56 beaches that existed in Rio at the beginning of the 20th century and today only survive in old photos and historical maps.
Among the best known are:
- Praia do Russel, in Glória, where Hotel Glória is located today.
- Praia da Saúde, which gave its name to the neighborhood.
- Praia de São Cristóvão, where the sea entered right into the neighborhood.
- Praia do Calabouço, where the landfill near Santos Dumont is located today.
- Praia da Lapa, which provided direct access to the sea from the neighborhood now famous for its arches.
Barbosa observes an important pattern. Landfills concentrated in the South Zone and Downtown, areas that gained economic value, while the North Zone and the suburbs were less transformed. This had two effects. First, it redistributed land value in a profoundly unequal way. Second, it practically made an entire suburban culture linked to the sea disappear, with yacht clubs, regattas, and artisanal fishing that existed in neighborhoods like Penha, Olaria, and Bonsucesso.
The hidden cost of expansion
There is also a third, more technical, effect of landfills: urban drainage.
When a city expands into areas that were once sea, lagoon, or swamp, it simultaneously creates habitable land and a hydraulic problem. The waters that once flowed freely through the natural terrain now need to be diverted by artificial drainage systems. During intense rains, this system often fails.
Much of Rio’s chronic flooding points coincide with old areas of sea, lagoon, or swamp. Downtown, Lapa, Cidade Nova, parts of Catete and Glória, areas near Maracanã: all these points have in common the fact that they exist today on land that, one or two centuries ago, was water.
What remains of the original landscape
For those who want to see, with their own eyes, marks of the original Rio, some points still allow the exercise.
The Church of Our Lady of Glory of Outeiro, in Outeiro da Glória, was a small hill located on the beach. Today, it is hundreds of meters from the sea. The Convent of Santo Antônio, in Downtown, stands on what remains of the hill of the same name. The Pedra do Sal, in Saúde, was a maritime boarding point. Today, it is surrounded by dry land.
In some cases, the neighborhood’s name remains the only clue. Praia Vermelha, in Urca, still exists and keeps its name. But the entire Urca is a 1922 landfill, with material coming from the dismantling of Morro do Castelo. In other words, the beach that remained there has always been there. The surrounding neighborhood was built on the sea.
Why this matters in 2026
The debate about Rio’s landfills returned to social media this year for two reasons. The first is the 60th anniversary of Aterro do Flamengo, completed in October 2025. The second is a growing discussion about the impacts of rising sea levels predicted for coastal cities in the coming decades.
A recent study by the University of Cambridge, released in 2025, confirmed for the first time, with two decades of data, that a mass of warm water is advancing towards Antarctica’s ice shelves at 1.26 kilometers per year. If projections are confirmed, the total possible rise in ocean levels could reach 58 meters in the long term. For Rio, this would ironically mean the reverse of everything that has happened in the last 250 years.
The sea would return, in part, to where it always was.
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