Since the dawn of time, humans have sought not only shelter but also stability, efficiency, and beauty in the places they inhabit. However, geography and climate have not always been allies: raging rivers, arid deserts, unstable terrain, active volcanoes, inaccessible mountains, or frozen permafrost have posed challenges that seemed insurmountable. And yet, it is precisely in these extreme contexts that architecture has revealed its most surprising face: that of creative adaptation.

This article is a journey through some of the world’s most fascinating and improbable cities, built in extreme environmental conditions or with construction techniques that push the boundaries of what is possible. From the “Manhattan of the Desert” in Yemen to the caves carved into the tuff rock in Matera, from cities suspended over the permafrost of Alaska and Iceland to the rock complexes of Georgia and Jordan, each example tells a different but unified story: that of a civilization that has learned to listen to its environment, understand its limits, and turn them into resources.

These architectures are not merely historical testimonies or tourist curiosities: they are living laboratories, models of sustainability and design intelligence that, in times of climate crisis and wild urbanization, offer valuable lessons once again. Analyzing how these cities were born and how they function means not only understanding the past but imagining future solutions inspired by an ancient art: that of building with what one has, and where it would seem impossible.

Shibam (Yemen): the “Manhattan of the Desert”

Dating back to the 16th century, Shibam rises like a mirage in the heart of the Wadi Hadramaut valley: a walled urban core where residential towers made of sun-dried mud bricks soar several dozen meters high. Each building — up to seven stories — is made with adobe, periodically reinforced with a fresh layer of mud plaster. The narrow, shaded streets are designed to channel cooling air currents into interior courtyards, applying the “obelisk trumpet” principle seen in other desert traditions. Maintenance is continuous: every year before the rainy season, the community gathers to replaster and consolidate the facades — a collective ritual that sustains the social as much as the architectural fabric.

Petra (Jordan): the rose-red city carved in rock

Designed by the Nabataeans starting in the 4th century BCE, Petra is a masterpiece of rock-cut engineering. Carved into the rose-colored sandstone of the Edom mountains, the city is best known for the monumental Khazneh, a two-tiered portico adorned in Hellenistic style. But perhaps even more remarkable is its hydraulic system: a complex network of channels, cisterns, and dams collected the desert’s sparse rainwater, enabling both water supply and protection from flash floods. The ruins indicate high population density, with homes and storage spaces carved at multiple levels, connected by stairways and narrow passages that exploit the natural canyon structure.

Vardzia (Georgia): the monastic labyrinth in the mountain

In the 12th century, Queen Tamar commissioned Vardzia, a vast rock-hewn settlement along the Kura River gorge. Over 600 caves stretch across thirteen levels, including frescoed churches, monastic cells, and wine-making facilities. This “rock hotel” was self-sufficient: a derived channel collected water upstream and directed it through underground galleries to fountains and a hypocaust heating system. The interior walls still preserve vivid biblical scenes painted on plaster using local pigments — evidence of a blend of Byzantine art and Caucasian traditions.

Whittier (Alaska, USA): the silo city under one roof

Isolated from storms and freezing temperatures, Whittier made a radical choice: housing nearly its entire population (around 200 people) in a massive multi-use building, the Begich Towers. Built in the 1960s as a military base, this twelve-story structure hosts apartments, offices, a grocery store, and even an indoor harbor for fishing boats. Its foundations rest on steel piles insulated from the permafrost via forced-air ventilation systems that prevent the underlying ice from melting. This “fossil condominium” minimizes heat loss, fosters social cohesion, and cuts maintenance costs in a climate where temperatures regularly drop below −30 °C.

Djenné (Mali): the world’s largest mud-brick city

At the crossroads of ancient trade routes, Djenné is renowned for the Great Mosque, the largest adobe building ever constructed. Originally built in the 13th century and rebuilt in 1907, the mosque stands out for its towers topped with pinnacles and wooden beams (torons), used for scaffolding during the annual “Crépissage,” a collective restoration event where the entire community reapplies fresh mud to the walls. The surrounding houses use the same materials and techniques, creating a uniformly ochre urban landscape. The mix of earth, sand, and straw ensures thermal insulation and durability, provided it is maintained regularly during the rainy season.

Singapore: the high-tech vertical forest

In a land scarce in natural resources, the “Garden City” has embraced bioclimatic architecture and green engineering to mitigate equatorial heat and humidity. The Supertree Grove at Gardens by the Bay features “trees” up to 50 meters tall, covered in photovoltaic panels and equipped with rainwater harvesting systems that feed skylights and evaporative cooling systems. Skyscrapers are connected by elevated walkways, creating shaded corridors and air channels; many buildings incorporate ventilated facades, green balconies, and rooftop gardens to reduce solar radiation. This model shows how the integration of nature and technology can redefine the very concept of an urban skyline, transforming it into a living ecosystem.

Matera (Italy): the cave city carved in tuff

Matera’s “cave houses,” inhabited since the Paleolithic era, are a perfect example of human adaptation to local geological resources. Carved into the soft tuff of the limestone hills, these dwellings use the rock mass as natural insulation: temperatures stay mild in winter and cool in summer. The seemingly chaotic urban layout served defensive purposes in the Middle Ages, reusing ancient tunnels to move safely during invasions. In recent decades, a restoration project has integrated modern plumbing, electricity, and climate systems using minimal engineering, preserving the rock surfaces and historical layers. Today, Matera is a UNESCO World Heritage Site for its unique cultural landscape, where stone becomes architrave, wall, and floor in an open-air museum.

Naples (Italy): the city built on an underground maze

Beneath the baroque alleys and Renaissance buildings of Naples lies a world of tunnels, Roman cisterns, and tuff quarries — a “second level” that has shaped the city’s architectural evolution. Large Greek-Roman era kilns once excavated tuff for brick production, leaving behind vast cavities later converted into early Christian catacombs and WWII bomb shelters. The surface buildings rest on reinforced underground vaults, while water — channeled through ancient decanters — feeds fountains and once supplied thermal baths. Recent geotechnical studies have mapped the hypogeum system and enabled localized structural reinforcements, preserving the historic stratification that makes Naples a vertical archipelago of ancient and modern.

Reykjavík (Iceland): the geothermal city between ice and fire

Founded in 1786 on a stretch of volcanic coast, Reykjavík stands out for its deep integration of geothermal energy into urban architecture. Hundreds of thermal wells channel hot water and steam into district heating networks, covering over 99% of the city’s energy needs with near-zero CO₂ emissions. Iconic buildings like Hallgrímskirkja church use local materials — reflective white concrete — that withstand glacial cold and enhance light during long winter nights. To counter seismic instability and discontinuous permafrost, foundations include elastic dampers and real-time monitoring systems that isolate structures from tremors. The result is a capital that, despite being exposed to a volatile volcanic landscape, offers a replicable model of resilience and energy sustainability in other extreme environments.