For centuries, cities were built under a clear premise: to domesticate territory. Rivers were channeled, wetlands drained, and soils sealed beneath asphalt. The modern urban landscape was designed to minimize the unpredictability of nature. In recent decades, however, a new idea has begun to challenge that paradigm: urban rewilding.

Faced with the limits of entirely artificial planning, urban planners and ecologists are exploring a different strategy—allowing certain natural processes to return to the urban fabric. This approach, known as rewilding or renaturalization, focuses not on managing every element of the environment but on restoring the conditions that allow ecosystems to reorganize themselves.

Although the concept first emerged in large-scale conservation projects, it is now finding compelling applications within cities. Urban environments, long viewed as separate from nature, are increasingly being reimagined as hybrid ecological systems.

From Conservation to Rewilding

The term rewilding began to take shape in the 1990s within the field of conservation biology. Traditional models focused on protecting specific species or maintaining landscapes in relatively stable states. Rewilding proposes something more ambitious: restoring the ecological interactions that enable ecosystems to self-regulate.

Ecosystems are not fixed structures. They are dynamic networks of relationships among species, vegetation, soil, water, and climate. When those relationships are disrupted—through habitat fragmentation, the disappearance of predators, or intensive land use—the system loses part of its ability to maintain equilibrium.

Rewilding seeks to restore those connections. In its most widely recognized form, the strategy relies on three elements:

• Large protected natural areas
• Ecological corridors connecting those territories
• Key species capable of reshaping ecosystem dynamics, especially large predators

These species play a crucial role because their influence extends throughout the entire food chain.

Ecological Cascades

One of the most frequently cited examples occurred in Yellowstone National Park in the United States. For much of the twentieth century, wolves had disappeared from the park. Without them, elk populations grew unchecked, leading to overgrazing that severely damaged vegetation along rivers and valleys.

In 1995, wolves were reintroduced. The effects extended far beyond the predator–prey relationship. The presence of wolves altered elk behavior, causing them to avoid certain areas of the park. This allowed willows and aspens to regenerate along riverbanks.

As vegetation recovered, beavers, birds, and numerous other species returned. Even some waterways stabilized as tree roots strengthened the riverbanks.

This phenomenon—known as a trophic cascade—demonstrates how the presence or absence of key species can reorganize an entire ecosystem.

When Nature Returns to the City

Although rewilding is often associated with vast natural landscapes, some of its most intriguing applications are emerging within cities. For decades, urban planning attempted to exclude nature from built environments.

Urban rewilding proposes the opposite: reintegrating ecological processes into the urban system. This may involve restoring rivers that were buried beneath infrastructure, transforming former industrial land into living landscapes, or allowing certain spaces to evolve through natural ecological succession.

Rather than recreating an idealized version of nature, the goal is to restore self-sustaining ecological dynamics.

Freshkills Park: From Landfill to Ecosystem

On Staten Island, New York, one of the world’s most ambitious urban ecological restoration projects is underway. For decades, Fresh Kills was the largest landfill in the United States, receiving more than 29,000 tons of waste per day.

Beginning in the early 2000s, the site began a transformation into a nearly 900-hectare ecological park, larger than Central Park. The process involved sealing the landfill with layers of impermeable membranes and clay to isolate the waste from surface soil.

Clean soil was then added, and native plant species were introduced to stabilize the terrain. Over time, the area began to function as an emerging ecosystem. Grasslands now attract migratory birds, small mammals, and insects, while the park captures methane gas produced by decomposing waste and converts it into energy.

A landscape once defined by environmental degradation is gradually evolving into a living ecological system.

Cheonggyecheon: The Return of an Urban River

Another remarkable example can be found in central Seoul, South Korea. For much of the twentieth century, the Cheonggyecheon River disappeared beneath layers of concrete and an elevated highway.

In the early 2000s, local authorities decided to remove the roadway infrastructure and restore the river. The project included reconstructing the watercourse and reintroducing riparian vegetation to stabilize the banks and improve water quality.

Over time, fish, birds, and insects returned to the area. Today, Cheonggyecheon functions both as a public space and ecological infrastructure. Beyond its environmental value, the river acts as a thermal regulator, as water and vegetation reduce local temperatures and help mitigate the urban heat island effect.

The Future of Cities

Projects like these reflect a profound shift in the way cities are conceived. For much of the twentieth century, urban design sought to control—or exclude—natural processes. Urban rewilding introduces a different logic: recognizing that ecological processes can play an active role in urban infrastructure.

Restored rivers, urban wetlands, green corridors, and landscapes evolving through natural succession can help regulate temperature, absorb carbon, manage rainwater, and restore biodiversity.

In a world shaped by climate change and rapid urban growth, renaturalization is not a romantic return to the past. It is a strategy for building more resilient cities. The challenge for contemporary urbanism may no longer be to dominate nature completely—but to learn, once again, how to coexist with it.